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What are the chemical elements that 
form most of living biological matter? 
The chemical elements that form most 
of the molecules of living beings are 
oxygen (O), carbon (C), hydrogen (H) 
and nitrogen (N).
• Glucose and fructose are examples of 
A. double sugars 
B. disaccharides 
C. single sugars 
D. polysaccharides
• What are described as the "building 
blocks of Protein"? 
A. Fiber 
B. Lipids 
C. Amino Acids 
D. Nutrients
• (CH2O)n is the molecular formula for 
which type of macromolecules? 
A. Proteins 
B. Lipids 
C. Carbohydrates 
D. Nucleic Acid
• Which macromolecule does not 
dissolve in water? 
A. proteins 
B. lipids 
C. carbohydrates 
D. nucleic acids
• What type of organic substances are 
fats? 
A. nucleic acid 
B. carbohydrate 
C. protein 
D. lipids
• What are the monomers of lipids? 
A. Amino acids 
B. Simple sugars 
C. Fatty acids and glycerol 
D. Nucleic acids
• Which of the following is a polymer? 
A. nucleic acid 
B. fatty acid 
C. Amino acid 
D. Glycerol
• Proteins are ____ made of amino 
acid ____ . 
A. monomers; polymers 
B. polymers; polypeptides 
C. polymers; monomers 
D. monomers; molecules
• Which of the following is NOT a 
polysaccharide? 
A. Glycogen 
B. Starch 
C. Sucrose 
D. Cellulose
• What are used in animals as a source of 
quick energy that can be stored in the 
liver and muscles ? 
A. Proteins 
B. Nucleic acids 
C. Carbohydrates 
D. Lipids
• Fats that have fatty acids with only single 
covalent bonds in their carbon skeletons 
are 
A. saturated 
B. unsaturated 
C. found in plants instead of animals 
D. liquid at room temperature
• Sugars, starches, and cellulose belong 
to which major class of biological 
molecules? 
A. Nucleic acids 
B. carbohydrates 
C. lipids 
D. polypeptides
• Plants like sugar cane and sugar beets store 
the energy as simple sugars. Other plants, 
like corn and potatoes, store the energy as 
more complex sugars called? 
A. carbohydrates 
B. calories 
C. starches 
D. cellulose
• This biological macromolecule is 
responsible for controlling the activity of the 
cell, and it stores and transports genetic 
information. 
A. Carbohydrate 
B. Nucleic acid 
C. Water 
D. Glucose
• In this type of structure, most of carbonyl 
groups of peptide bonds forms a hydrogen 
bond with the amide nitrogen of another 
peptide bond four amino acids further down 
the polypeptide chain: 
A. Alpha-helix 
B. Beta-sheet 
C. Beta-turn 
D. Quaternary
• Lipids are used by the body to perform all 
of the following functions EXCEPT: 
A. membrane structural material. 
B. enzyme action. 
C. insulation. 
D. a rich energy source.
• What is the 
constitutional unit of 
proteins? 
• What is the primary 
structure of a 
protein? 
• The constitutional 
units of proteins are 
the amino acids. 
• The primary protein 
structure is the linear 
sequence of amino 
acids that form the 
molecule.
What is the secondary structure of a 
protein? 
• The secondary protein structure is generated by 
the manner its amino acids interact through the 
inter-residue bond. These interactions create a 
spatial conformation of the polypeptide filament. 
The two most studied secondary conformations 
of proteins are the alpha-helix and the beta-sheet.
• The isoelectric point of an amino acid is defined 
as the pH 
A. where the molecule carries no electric charge 
B. where the carboxyl group is uncharged 
C. where the amino group is uncharged 
D. of maximum electrolytic mobility
• When the amino acid alanine (R-group 
is CH3) is added to a solution 
with a pH of 7.3, alanine becomes 
A. a cation 
Isoelectric 
B. nonpolar 
point of 
C. a zwitterions 
alanine is 
D. an anion 
6.00
• The term “SALTING IN” refers to? 
A. Changes in an amino acid’s isoelectric 
point. 
B. Increasing the solubility of a protein in 
solution by adding ions. 
C. The use of a liquid bridge in an 
electrochemical cell. 
D. The ionization of a strong acid.
Salting Out (by solubility) 
• Most proteins are less soluble at high salt concentrations, an effect 
called salting out. 
• The salt concentration at which a protein precipitates differs from 
one protein to another. Hence, salting out can be used to fractionate 
proteins. 
• Dialysis can be used to remove the salt if necessary.
• The local spatial arrangement of a 
polypeptide’s backbone atoms without regard 
to the conformation of its side chains can be 
called as 
A. Primary structure 
B. Secondary structure 
C. Tertiary structure 
D. Quaternary structure
• Which of the following amino acids are 
more likely to be found in a protein’s 
interior away from aqueous solvent 
molecules? 
A. Val, Leu, Ile, Met, and Phe 
B. Ser, Thr, Asn, Gln, and Tyr 
C. Arg, His, Lys, Asp, and Glu 
D. All of the above.
• Which of the following is (are) true of b- 
turns in proteins? 
A. It is a 180º turn of four amino acids. 
B. Glycine and proline are frequently 
found there. 
C. Are used as connecting turns of a- 
helix 
D. All of the above.
• The primary stabilizing force of 
protein secondary structure is: 
• A Ionic bonds. 
• B Covalent bonds. 
• C Van der Waals forces. 
• D Hydrogen bonds
• Two types of b-pleated sheets can be 
called: 
• A parallel and antiparallel 
• B left-handed and right-handed. 
• C Fand Y 
• D α and β
• Which of the following is NOT a characteristic 
of a globular protein? 
• A Polypeptide chain in extended, long 
sheets 
• B Polypeptide chains are folded in a 
spherical shape. 
• C Contains several types of secondary 
structure 
• D Typical for regulatory proteins.
• Which of the following statements regarding 
ligand binding is NOT correct? 
A. Some proteins require ligands in order to 
perform their function 
B. Enzymes with their attached ligands are 
called holoenzymes 
C. Ligands are synonymous with prosthetic 
groups 
D. The heme group on hemoglobin is an 
example of a tightly bound ligand
• The alpha helix found in myoglobin can 
best be described as 
A. Primary structure 
B. Secondary structure 
C. Tertiary structure 
D. Motif structure
• Some parts of a protein that have a specific 
chemical structure and function are called 
protein 
A. chemicals 
B. domains 
C. subunits 
D. enzymes
• One of the following is NOT usually a 
force that helps to hold the monomer 
units of a quaternary protein together? 
A. Peptide bonds 
B. Disulfide bonds 
C. Salt bonds 
D. Hydrophobic interactions
What is the quaternary structure of a protein? 
Do all proteins have quaternary structure? 
• The quaternary protein structure is the spatial 
conformation due to interactions among 
polypeptide chains that form the protein. 
• Only those proteins made of two or more 
polypeptide chains have quaternary structure.
What is protein denaturation? Is there any 
change in the primary structure when a protein 
is denatured? What are some factors that can 
lead to protein denaturation? 
• Secondary, tertiary and quaternary structures of proteins 
are spatial structures. Denaturation is modification in any 
of these spatial structures that makes the protein 
deficient or biologically inactive. 
• After denaturation the primary protein structure is not 
affected. 
• Protein denaturation can be caused by temperature 
variation, pH change, changes in the concentration of 
surrounding solutes. Most proteins denature after certain 
elevation of temperature or when in very acid or very 
basic solutions.
• Which of the following terms describes 
hemoglobin but not myoglobin? 
A. The protein contains hydrogen bonds 
B. The protein contains a hydrophobic 
pocket that contains heme 
C. Imidazole groups stabilize the ferrous 
ion 
D. The protein contains alpha and beta 
chains
• Of the following states of hemoglobin 
(Hb), which is least likely to bind the next 
molecule of oxygen (O2)? 
A. Hb 
B. Hb (O2) 
C. Hb (O2)2 
D. Hb (O2)3
• If a person breathes into a paper bag, you 
would expect their blood CO2 to 
A. decrease and their blood pH to increase 
B. decrease and their blood pH to decrease 
C. increase and their blood pH to increase 
D. increase and their blood pH to decrease
• The quaternary structure of a protein is 
A. the sequence of amino acids in the 
polypeptide 
B. the coiling or folding of the polypeptide 
C. the intertwining of two or more polypeptides 
D. the 3-dimensional appearance of the 
polypeptide
• The action of disrupting the three-dimensional 
shape of a protein is 
termed 
A. dehydration 
B. denaturation 
C. deamination 
D. hydrolysis
SSaammppllee qquueessttiioonnss 
• At a pH >pI of a given protein, that protein 
becomes ______, at the pH<pI of that 
same protein, it becomes _______. 
negatively charged (an anion) 
positively charged (a cation) 
The isoelectric point (pI) is the pH at which a particular molecule or surface 
carries no net electrical charge.
SSaammppllee qquueessttiioonnss 
• What is the prosthetic group that hemoglobin and 
myoglobin's oxygen binding ability depend on? 
Heme 
• Define cooperativity relative to binding oxygen 
binding of oxygen at one site increases chances 
of binding oxygen at the other sites; loss of an 
oxygen at one site increases the chances of 
losing oxygen at the other sites 
• What are the two states of the hemoglobin quaternary 
structure? And what are their characteristics? 
T state = taut (deoxy form) 
R state = relaxed (oxygenated form)
Sample questions 
• The imino acid found in protein structure 
• (a) Arginine 
• (b) Proline 
• (c) Histidine 
• (d) Lysin
• The bonds in protein structure that are 
not broken on denaturation. 
• (a) Hydrogen bonds 
• (b) Peptide bonds 
• (c) lonic bond 
• (d) Disulfide bonds
• Which of the following 
is not considered a 
pyrimidine? 
A. C 
B. T 
C. U 
D. G 
• What type of sugar is 
found in the 
nucleotides of DNA? 
A. deoxyribose 
B. ribose 
C. glucose 
D. none of the above
• What is the role of hydrogen bonds in 
the structure if DNA? 
A. to code for proteins 
B. to synthesize proteins 
C. to separate the strands 
D. to connect the base pairs
Which type of chemical bond maintains the 
pairing of each chain in the DNA molecule? 
• To form the DNA molecule, purine bases 
bind to pyrimidine bases by intermolecular 
bonds called hydrogen bonds. Hydrogen 
bonds occur when there is hydrogen near 
one of these electronegative elements: 
oxygen or nitrogen.
Sample questions for the nucleic acid section 
Nucleoside is a pyrimidine or 
purine base 
• A.covalently bonded to a 
sugar 
• B.ionically bonded to a sugar 
• C.hydrogen bonded to a sugar 
• D.none of the above 
The sugar in RNA is ______ , the 
sugar in DNA is _____ 
• A.deoxyribose, ribose 
• B.ribose, deoxyribose 
• C.ribose, phosphate 
• D.ribose, uracil
Sample questions for the nucleic acid section 
In gel electrophoresis, what 
fragments will move most 
quickly through a gel? 
• A.Large fragments 
• B.Small fragments 
• C.Large genome 
• D.None of these 
Nucleotide bases and 
aromatic amino acids 
absorb light respectively at 
• A.280 and 260 nm 
• B.260 and 280 nm 
• C.270 and 280 nm 
• D.260 and 270 nm
Sample questions for the nucleic acid section 
Which of the following is found 
on RNA but not DNA? 
• A.Uracil 
• B.Deoxyribose 
• C.Phosphate 
• D.Adenine 
Which is true about the pairing of 
bases in the DNA molecule? 
• A. purines always pair with 
pyrimidines 
• B. a single ring base pairs with 
another single ring base 
• C. a double ring base pairs with 
another double ring base 
• D. purines pair with purines and 
pyrimidines with pyrimidines
Sample questions for the nucleic acid section 
A messenger acid is 336 nucleotides 
long, including the initiator and 
termination codons. The maximum 
number of amino acids in the 
protein translated from this mRNA 
is: 
• A 999 
• B 630 
• C 330 
• D 111 
• E 110 
With what mRNA codon would the 
tRNA in the diagram be able to 
form a codon-anticodon base 
pairing interaction? 
• A. 3'-AUG-5' 
• B. 3'-GUA-5' 
• C. 3'-CAU-5' 
• D. 3'-UAC-5' 
• E. 3'-UAG-5'
Sample questions for the nucleic acid section 
• Of what units are nucleic acids constituted? What are the 
chemical entities that compose that unit? 
• What is the rule for the pairing of nitrogenous bases in 
the DNA molecule? And in the RNA? 
• For each of the following structures identify: the 
carbohydrate (ribose or deoxyribose)?; nucleoside or a 
nucleotide? DNA or a RNA system?
Sample questions 
What is the function of enzymes within living systems? 
• A) structural elements 
• B) neurotransmitters 
• C) catalysts 
• D) hormones 
Enzymes have names that 
• A) always end in -ase 
• B) always end in -in 
• C) can end either in -in or -ase 
• D) can end in either -in or -ogen
Sample questions 
The protein portion of a conjugated enzyme is called a(n) 
• A) apoenzyme. 
• B) coenzyme. 
• C) holoenzyme. 
• D) cofactor. 
Which of the following could be a component of a conjugated enzyme? 
• A) coenzyme 
• B) cofactor 
• C) apoenzyme 
• D) more than one correct response 
• E) no correct response
Sample questions 
Enzyme cofactors that bind covalently at the active site of an enzyme 
are referred to as _________. 
• (a) cosubstrates. 
• (b) prosthetic groups. 
• (c) apoenzymes. 
• (d) vitamins
Sample questions 
Which of the following statements concerning the effect of temperature 
change on an enzyme-catalyzed reaction is correct? 
• A) An increase in temperature can stop the reaction by denaturing 
the enzyme. 
• B) An increase in temperature can increase the reaction rate by 
increasing the speed at which molecules move. 
• C) An increase in temperature to the optimum temperature 
maximizes reaction rate. 
• D) more than one correct response 
• E) no correct response
Sample questions 
• A catalyst can promote product formation during a chemical reaction 
by _____. 
• (a) lowering the activation energy barrier. 
• (b) stabilizing the transition state. 
• (c) positioning reactants in the correct orientation. 
• (d) bringing reactants together. 
• (e) all of the above 
Which of the following is characteristic of an enzyme catalyst? 
• (a) It positions reactants in the correct orientation. 
• (b) It lowers the activation energy barrier. 
• (c) It binds the transition state tighter than the substrate. 
• (d) all of the above
Sample questions 
An enzyme active site is the location in the enzyme where 
• A) protein side groups are brought together by bending and folding 
to form a site for interactions with substrates 
• B) the catalyst interactions with the enzyme 
• C) catalyst molecules are generated 
• D) the substrate creates the catalyst molecules 
An enzyme active site is the location in an enzyme where substrate 
molecules 
• A) are generated. 
• B) become catalysts. 
• C) undergo change. 
• D) more than one correct response 
• E) no correct response
• For the enzyme reaction A+ B = C + D, Delta Go' = + 1 
kcal/mol. This reaction will proceed spontaneously in a 
forward direction if: 
A. The concentration of C is increased one-hundred fold 
B. The concentration of A is increased one-hundred fold 
C. The concentration of B is lowered one-hundred fold 
D. The concentration of both A and D are increased one-hundred 
fold
• Which of the following statements about enzymes or 
their function is true? 
A. Enzymes do not alter the overall change in free 
energy for a reaction 
B. Enzymes are proteins whose three-dimensional form 
is key to their function 
C. Enzymes speed up reactions by lowering activation 
energy 
D. All of the above
• What is the optimal temperature range 
for the majority of enzymes? 
A. 40-55 ℃ 
B. 35-40 ℃ 
C. 25-30 ℃ 
D. 15-20 ℃
• An allosteric activator 
A. increases the binding affinity 
B. decreases the binding affinity 
C. stabilizes the R state of the protein 
D. both (a) and (c)
• Reactants of an enzyme-catalyzed 
reaction are known as 
A. products 
B. substrates 
C. proteins 
D. complex
• The location on an enzyme where 
binding occurs is known as the 
A. action point 
B. enzyme 
C. binding location 
D. active site
• Enzymes catalyze reactions by 
A. Increasing the free energy of the system so that the 
change in free energy is positive 
B. Increasing the free energy of the substrate so that it is 
greater than the free energy of the product 
C. Changing the equilibrium constant for the reaction 
D. Decreasing the free energy of activation
• An apoenzyme 
A. Includes non-protein compounds such as metal ions 
B. Consists of complex organic structures which may be 
classified as activation-transfer coenzymes or oxidation-reduction 
coenzymes 
C. Is the protein portion of the enzyme without the 
cofactors 
D. None of the above
• NAD+, FAD, and FMN are all cofactors 
for: 
A. Oxidoreductases 
B. Transferases 
C. Hydrolases 
D. Ligases
• At the end of a chemical reaction 
A. an enzyme's structure is altered 
B. an enzyme is detached from the product, 
has its original structure, and can catalyze 
more chemical reactions 
C. the enzyme loses its ablity to catallyze other 
chemical reactions 
D. the enzyme remains attached to the 
products
Sample questions 
The rate of a second order reaction depends on the concentration of 
_________. 
• (a) one substrate 
• (b) two substrates 
• (c) three substrates 
• (d) none of the above
Rate constants and reaction order 
Rate constant (k) measures how rapidly a reaction occurs 
k1 
k-1 
A B + C 
Rate (v, velocity) = (rate constant) (concentration of reactants) 
v= k1 [A] 
1st order reaction (rate dependent on concentration of 1 reactant) 
v= k-1[B][C] 
2nd order reaction (rate dependent on concentration of 2 reactants) 
Zero order reaction (rate is independent of reactant concentration)
• On the following plot, N represents the curve for an 
allosteric enzyme with no allosteric activators or 
inhibitors added. If an allosteric activator was added, 
which curve would one obtain? 
A. Curve A 
B. Curve B 
C. Curve C 
D. Curve D
• Which of the following statements about 
allosteric enzymes is CORRECT? 
A. The binding of substrate to any active site 
affects the other active sites 
B. The plot of initial velocity vs. substrate 
concentration is a straight line 
C. The Keq of the reaction is increased when 
allosteric activator is bound 
D. The enzymes contains only one polypeptide 
chain
Enzyme kinetics
Sample questions 
Which of the following kinetic parameters best describes how 
well suited a specific compound functions as a substrate 
for a particular enzyme? 
• (a) Km 
• (b) Vmax 
• (c) kcat 
• (d) kcat/Km
Short summary 
• Km  substrate specificity; substrate binding 
• kcat,  the turnover number 
• kcat/Km  the catalytic efficiency
Sample questions 
The rate-determining step of Michaelis Menten kinetics is 
• A.the complex formation step 
• B.the complex dissociation step to produce product 
• C.the product formation step 
• D.Both (a)and(c)
• A competitive inhibitor of an enzyme works by 
A. fitting into the enzyme's active site 
B. fitting into the allosteric site of the enzyme 
C. attaching itself to the substrate, thereby preventing 
the enzyme from making contact with substrate 
D. increasing the activation energy of the enzyme-catalyzed 
reaction
• If an enzyme is described by the Michaelis- 
Menten equation, a competitive inhibitor will: 
A. decrease the Km and decrease the Vmax 
B. decrease the Km, but not the Vmax 
C. always just change the Vmax 
D. increase the Km but not change the Vmax
• The most likely effect of a non-competitive 
inhibitor on an Michaelis-Menten enzyme 
is to 
A. Increase the Vmax 
B. Decrease the Vmax 
C. Increase both the Vmax and the Km 
D. Decrease both the Vmax and the Km
• Competitive inhibitor: Vmax stays the same, but Km increases 
• Non-competitive inhibitor decreases the turnover number of the 
enzyme rather than preventing substrate binding- Vmax decreases 
but Km stays the same. This cannot be overcome with an increase 
in substrate concentration.
Sample questions 
Which of the following binds to an enzyme at its active site? 
• A) irreversible inhibitor 
• B) reversible competitive inhibitor 
• C) reversible noncompetitive inhibitor 
• D) more than one correct response 
• E) no correct response 
An uncompetitive inhibitor binds to _____. 
• (a) E 
• (b) ES 
• (c) P 
• (d) a and b 
• (e) a and c
Sample questions 
A reversible inhibitor that can bind to either E alone or the ES complex 
is referred to as a _____. 
• (a) competitive inhibitor. 
• (b) non-competitive inhibitor. 
• (c) uncompetitive inhibitor. 
• (d) suicide inhibitor. 
• (e) irreversible inhibitor.
Sample questions 
A competitive inhibitor of an enzyme is usually 
• A.a highly reactive compound 
• B.a metal ion such as Hg2+ or Pb2+ 
• C.structurally similar to the substrate. 
• D.water insoluble 
The enzyme inhibition can occur by 
• A.reversible inhibitors 
• B.irreversible inhibitors 
• C.Both (a) and (b) 
• D.None of these
Sample questions 
In a Lineweaver-Burk Plot, competitive 
inhibitor shows which of the following 
effect? 
• A.It moves the entire curve to right 
• B.It moves the entire curve to left 
• C.It changes the x-intercept 
• D.It has no effect on the slope
Sample questions 
Non-competitive inhibitor of an enzyme catalyzed 
reaction 
• A.decreases Vmax 
• B.binds to ES 
• C.both (a) and (b) 
• D.can actually increase reaction velocity in rare 
cases
Sample questions 
A classical uncompetitive inhibitor is a compound that binds 
• A.reversibly to the enzyme substrate complex yielding an 
inactive ESI complex 
• B.irreversibly to the enzyme substrate complex yielding an 
inactive ESI complex 
• C.reversibly to the enzyme substrate complex yielding an 
active ESI complex 
• D.irreversibly to the enzyme substrate complex yielding an 
active ESI complex
Enzyme regulation
Sample questions 
• Two curves showing the rate versus substrate concentration are 
shown below for an enzyme catalyzed reaction. One ‐ curve is for the 
reaction in the presence of substance X. The other curve is for data 
in the absence of substance X. Examine the curves and tell which 
statement below is true. 
• A) The catalysis shows Michaelis‐Menten kinetics with or without X. 
• B) X increases the activation energy for the catalytic reaction. 
• C) X could be a competitive inhibitor. 
• D) X is an activator of the enzyme.
Sample questions 
Allosteric enzymes are 
• A.similar to simple enzyme 
• B.smaller than simple enzyme 
• C.larger and more complex than simple enzyme 
• D.smaller than simple enzyme but not complex 
Which statement is false about allosteric regulation? 
• A. It is usually the mode of regulation for the last step in reaction pathways 
since this step produces the final product. 
• B. Cellular response is faster with allosteric control than by controlling 
enzyme concentration in the cell. 
• C. The regulation usually is important to the conservation of energy and 
materials in cells. 
• D. Allosteric modulators bind non-covalently at sites other than the active 
site and induce conformational changes in the enzyme.
Sample questions 
Allosteric modulators seldom resemble the substrate or 
product of the enzyme. What does this observation 
show? 
• A) Modulators likely bind at a site other than the active 
site. 
• B) Modulators always act as activators. 
• C) Modulators bind non-covalently to the enzyme. 
• D) The enzyme catalyzes more than one reaction.
Sample questions 
• Some enzymatic regulation is allosteric. In such cases, 
which of the following would usually be found? 
• A) cooperativity 
• B) feedback inhibition 
• C) both activating and inhibitoryactivity 
• D) an enzyme with more than one subunit 
• E) the need for cofactors
Sample questions 
• Describe allosteric regulation of 
enzyme activity? 
An allosteric enzyme is one in which the activity of the enzyme can be 
controlled by the binding of a molecule to the “allosteric site”, somewhere 
other than the active site. Thus allosteric control of an enzyme can be 
classed in two ways. A positive allosteric regulation is the binding of a 
molecule to the enzyme which increase the rate of reaction. The opposite is 
a negative allosteric regulation. An example for this is phosphofructokinase, 
which is promoted by a high AMP concentration, and inhibited by a high ATP 
concentration.
• This small protein can have dramatic 
effects on the activities of enzymes in 
response to changes in intracellular 
calcium ion concentration: 
A. Calcitonin 
B. Calsequestrin 
C. Calmodulin 
D. Calcitriol
Non-covalent Interactions 
Protein-Protein Interactions 
• Calmodulin (CALcium MODULted proteIN) 
– Binding of Ca++ to calmodulin changes its 
shape and allows binding and activation of 
certain enzymes
Sample questions 
• Which statement is false about covalent modification? 
• A) It is reversible. 
• B) It is slower than allosteric regulation. 
• C) It is irreversible. 
• D) Phosphorylation is a common covalent modification.
Sample questions 
Protein kinases are enzymes that act on other enzymes by 
adding phosphates groups. When the enzyme is 
phosphorylated, it changes its activity (it becomes more 
or less active, depending on the enzyme). This 
regulatory mechanism of enzymatic activity is called: 
• A) Allosteric Control 
• B) Competitive inhibition 
• C) Covalent Modification 
• D) Isozymes Modification 
• E) Zymogen activation
Glycolysis
Sample questions 
• Glycolytic pathway regulation involves 
• A. allosteric stimulation by ADP 
• B. allosteric inhibition by ATP 
• C. feedback, or product, inhibition by ATP 
• D. all of the above 
• Why does the glycolytic pathway continue in the direction of 
glucose catabolism? 
• A. There are essentially three irreversible reactions that act as the 
driving force for the pathway 
• B. High levels of ATP keep the pathway going in a forward 
direction 
• C. The enzymes of glycolysis only function in one direction 
• D. Glycolysis occurs in either direction
Sample questions 
The released energy obtained by oxidation of glucose is stored as 
A. a concentration gradient across a membrane 
B. ADP 
C. ATP 
D. NAD+ 
A kinase is an enzyme that 
A. removes phosphate groups of substrates 
B. uses ATP to add a phosphate group to the substrate 
C. uses NADH to change the oxidation state of the substrate 
D. removes water from a double bond
Sample questions 
• For every one molecule of sugar glucose which is oxidized 
__________ molecule of pyruvic acid are produced. 
• A.1 
• B.2 
• C.3 
• D.4 
• The enzymes of glycolysis in a eukaryotic cell are located in the 
• A.intermembrane space 
• B.plasma membrane 
• C.cytosol 
• D.mitochondrial matrix
Sample questions 
• Which of the following is not true of glycolysis? 
• A.ADP is phosphorylated to ATP via substrate level 
phosphorylation 
• B.The pathway does not require oxygen 
• C.The pathway oxidizes two moles of NADH to NAD+ for each mole 
of glucose that enters 
• D.The pathway requires two moles of ATP to get started 
catabolizing each mole of glucose 
• ATP is from which general category of molecules? 
• A.Polysaccharides 
• B.Proteins 
• C.Nucleotides 
• D.Amino acids
Sample questions 
• Which of the following regulates glycolysis steps? 
• A.Phosphofructokinase 
• B.Hexose kinase 
• C.Pyruvate kinase 
• D.All of these
Sample questions 
• Which of the following is not a mechanism for altering the flux of 
metabolites through the rate-determining step of a pathway? 
• A. Allosteric control of the enzyme activity 
• B. Block active sites 
• C. Genetic control of the enzyme concentration 
• D. Covalent modification of the enzyme 
• Phosphofructokinase, the major flux-controlling enzyme of 
glycolysis is allosterically inhibited and activated respectively by 
• A.ATP and PEP 
• B.AMP and Pi 
• C.ATP and ADP 
• D.Citrate and ATP
• Where does glycolysis occur? 
A. inner membrane of mitochondria 
B. matrix of mitochondria 
C. stroma of chloroplast 
D. cytoplasm
• Sports physiologists wanted to monitor 
athletes to determine at what point their 
muscles were functioning anaerobically. They 
could do this by checking for a buildup of 
which of the following compounds? 
A. oxygen 
B. ATP 
C. lactate 
D. carbon dioxide
gluconeogenesis
Sample questions 
• There are four enzymes of gluconeogenesis that 
circumvent the irreversible steps in glycolysis. When 
starting with the substrate pyruvate or lactate they are 
• A. Hexokinase, phosphofructokinase-1, 
phosphofructokinase-2 and pyruvate kinase 
• B. Pyruvate carboxylase, phosphoenolpyruvate 
carboxykinase, fructose-1,6-bisphosphatase, and 
glucose-6-phosphatase 
• C. Glycerol kinase, glycerol-3-phosphate 
dehydrogenase, fructose-2,6-bisphosphatase, and 
glucose-6-phosphatase 
• D. Amino transferase, phosphoenolpyruvate 
carboxykinase, fructose-2,6-bisphosphatase, and 
glucose-6-phosphatase
Sample questions 
• The enzymes that remove phosphate groups during the 
process of gluconeogenesis and circumvent two of the 
three irreversible reactions of glycolysis are 
• A. Pyruvate kinase and glycerol kinase 
• B. Phosphoenolpyruvate carboxykinase and glycerol 
kinase 
• C. 3-Phosphoglycerate kinase and fructose-1,6- 
bisphosphatase 
• D. Fructose-1,6-bisphosphatase and glucose-6- 
phosphatase
Glycolysis <-> gluconeogenesis 
Gluconeogenesis is not the reversal of glycolysis !!! 
Glycolysis: in the cytosol 
Gluconeogenesis: major part in cytosol 
-> 1st step in mitochondria -> shuttle 
Biotin: prosthetic 
group -> carrier 
for CO2 
Reverse reaction of glycolysis thermodynamically 
not favorable !!! 
112
Sample questions 
• The most important control step in gluconeogenesis is fructose-1,6- 
bisphosphatase. All of the following statements are true EXCEPT 
• A. Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate 
to fructose-6-phosphate 
• B. During times when insulin is high, fructose-1,6-bisphosphatase is 
inhibited by fructose-2,6-bisphosphate 
• C. During a fast or exercise when glucagon and/or epinephrine are 
high, fructose-1,6-bisphosphatase is active because of the absence 
of fructose-2,6-bisphosphate 
• D. Glycolysis or gluconeogenesis cannot be active at the same 
time. If they were is would be a futile cycle
Sample questions 
• In the liver, glucagon will activate 
• A. Glycolysis and glycogen synthesis 
• B. Gluconeogenesis and glycogenolysis 
• C. Gluconeogenesis and glycogen synthase 
• D. Gluconeogenesis and glycogen synthesis 
• Which of the following statements about hormonal levels during different 
states is true? 
• A. During the time you are eating a high carbohydrate mixed meal, the 
insulin to glucagon ratio will decrease 
• B. When passing from the fed to fasting state, insulin and glucagon usually 
decrease 
• C. When playing basketball, epinephrine is usually low and insulin is high 
• D. After running for 20 miles, epinephrine and glucagon are high and insulin 
is low
Sample questions 
• All of the following will result in activation of glycogen 
phosphorylase in skeletal muscle EXCEPT 
• A. Increased concentrations of AMP from contraction of 
muscle 
• B. Increased epinephrine and cAMP 
• C. Increased cytosolic [Ca++] 
• D. Increased protein phosphatase 
• E. Increased activity of glycogen phosphorylase kinase
• All of the following statements concerning glycogen 
synthesis and glycogenolysis are true EXCEPT 
A. High blood glucose and high insulin will activate 
glycogen synthesis and inhibit glycogen phosphorylase 
B. A low insulin to glucagon ratio will activate glycogen 
phosphorylase and inhibit glycogen synthase 
C. Being hit in the head with a bat will activate glycogen 
synthesis and inhibit glycogen phosphorylase 
D. Taking this test will activate glycogen phosphorylase 
and inhibit glycogen synthase
Lipid metabolism
Sample question 
• Atherosclerosis can cause blood 
• A. thinning 
• B. blockage 
• C. thickening 
• D. none of these
Sample question 
• Ketosis is ascribed in part to: 
– A. Slowdown in fat metabolism 
– B. An insufficient intermediates of TCA cycle 
– C. An underproduction of acetyl-CoA 
– D. An inhibition of glycogen synthesis
Sample question 
• In the intestine, the dietary fats are hydrolyzed by 
• A.triacylglycerol lipase 
• B.adenylate cyclase 
• C.pancreatic lipase 
• D.protein kinase
Sample question 
• In eukaryotes fatty acid breakdown occurs in 
• A. mitochondrial matrix 
• B. cytosol 
• C. cell membrane 
• D. endoplasmic reticulum
Sample question 
• Fatty acid synthesis takes place in 
• A. mitochondria 
• B. cell membrane 
• C. cytosol 
• D. endoplasmic reticulum
Sample question 
• Chylomicrons are synthesized in 
• A. blood 
• B. liver 
• C. intestine 
• D. pancreas
Sample question 
• VLDLs are synthesized in 
• A. blood 
• B. liver 
• C. intestine 
• D. pancreas
Sample question 
• Cholestrol is the precursor of 
• A. steroid hormones 
• B. vitamin A 
• C. bile salts 
• D. both (a) and (c)
Oxidative phosphorylation
Sample Questions 
• A biological redox reaction always involves 
• A.an oxidizing agent 
• B.a gain of electrons 
• C.a reducing agent 
• D.all of these 
• Coenzyme Q is involved in electron transport as 
• A.directly to O2 
• B.a water-soluble electron donor 
• C.covalently attached cytochrome cofactor 
• D.a lipid-soluble electron carrier
Sample Questions 
• FAD is reduced to FADH2 during 
• A. electron transport phosphorylation 
• B. lactate fermentation 
• C. Krebs cycle 
• D. glycolysis 
• During glycolysis, electrons removed from glucose 
are passed to 
• A. FAD 
• B. NAD+ 
• C. acetyl CoA 
• D. pyruvic acid
Sample Questions 
• Almost all of the oxygen (O2) one consumes in 
breathing is converted to: 
• A.acetyl-CoA. 
• B.carbon dioxide (CO2). 
• C.carbon monoxide and then to carbon dioxide. 
• D.water. 
• The carbon dioxide is primary a product of 
• A.Krebs cycle 
• B.glycolysis 
• C.electron transport phosphorylation. 
• D.lactate fermentation.
Sample Question 
• Which of the following statements about the chemiosmotic theory 
is correct? 
• A. Electron transfer in mitochondria is accompanied by an 
asymmetric release of protons on one side of the inner 
mitochondrial membrane. 
• B. It predicts that oxidative phosphorylation can occur even in 
the absence of an intact inner mitochondrial membrane. 
• C. The effect of uncoupling reagents is a consequence of their 
ability to carry electrons through membranes. 
• D. The membrane ATP synthase has no significant role in the 
chemiosmotic theory.
Sample Question 
• Uncoupling of mitochondrial oxidative 
phosphorylation: 
• A. allows continued mitochondrial ATP 
formation, but halts O2 consumption. 
• B. halts all mitochondrial metabolism. 
• C. halts mitochondrial ATP formation, but 
allows continued O2 consumption. 
• D. slows the conversion of glucose to 
pyruvate by glycolysis.
Sample Questions 
• Where does Oxidative Phosphorylation 
occur? 
the inner membrane of the cell mitochondria 
• In the reaction in which FADH2 transfers 
hydrogen atoms to Q, which molecule is 
oxidized and which is reduced?
• Cellular respiration takes place 
mostly in: 
A. chloroplasts 
B. ribosomes 
C. nucleus 
D. mitochondria
• Which of the following is not present 
during the TCA cycle? 
A. NADH 
B. O2 
C. CO2 
D. ATP
• Which of the following is a list of the stages in 
the correct order? 
A. pyruvate oxidation, glyocolysis, the citric acid 
cycle, and oxidative phosphorylation 
B. oxidative phosphorylation, glyocolysis, the 
citric acid cycle, and pyruvate oxidation 
C. glycolysis, pyruvate oxidation, the citric acid 
cycle, and oxidative phosphorylation 
D. glycolysis, the citric acid cycle, pyruvate 
oxidation, and oxidative phosphorylation
• What are the products of the citric 
acid cycle? 
A. NADH, ATP, FADH2, and CO2 
B. O2, ADP, 1 FAD, and NAD+ 
C. Glucose, ATP, O2, and NADH 
D. heat, H2O, NADH, and pyruvate
• Which of the following is NOT a way of 
producing ATP in humans? 
A. Krebs Cycle 
B. Alcohol Fermentation 
C. Lactic Acid Fermentation 
D. Glycolysis
• Which of the following is an aerobic 
product of pyruvate catabolic 
metabolism? 
• A lactate 
• B ethanol. 
• C acetyl CoA 
• D glucose.
• Someone had hypoglycemic coma after he 
injected himself with a large dose of insulin. All 
of the following contributed to his coma EXCEPT 
A. Insulin inhibited gluconeogenesis in the liver 
B. Insulin activated glycogen phosphoryalse in 
the liver 
C. Insulin increased Glut4 in the muscle 
membrane 
D. Insulin inhibited the mobilization of free fatty 
acid from adipose and the entrance into liver 
mitochondria
• The insulin to glucagon ratio is low as it usually is in both 
Type I and Type II diabetics. During and immediately 
after a high carbohydrate meal, you would expect 
A. The storage of glucose in muscle to be less than 
normal for type 2 patients but normal for type 1 patients 
B. The storage of glucose in muscle to be less than 
normal for type 1 patients but normal for type 2 patients 
C. The storage of glucose in muscle and liver to be less 
than normal 
D. The storage of glucose in muscle and liver to be 
greater than normal
• All other things being constant, an 
increase in glucagon would result in an 
increase in 
A. Fatty acid synthesis in adipose tissue 
B. β-oxidation in liver 
C. Protein synthesis in muscle 
D. Glycogenolysis in muscle
• The pathway for the synthesis of glycogen 
from portal blood glucose in the liver: 
A. Is inhibited by glucose 
B. Is inhibited by insulin 
C. Uses activated glycogen phosphorylase 
D. Is inhibited by high cAMP
• Epinephrine: 
• A stimulates the synthesis of glycogen in 
liver cells. 
• B has no effect on cAMP in muscle cells 
• C has a direct effect on the glucose 
transporter in muscle cells. 
• D stimulates the degradation of glycogen 
in muscle cells.
• The TCA cycle: 
A. Is found in the cytosol 
B. Is controlled by the ADP/ATP ratio and the 
NADH concentration 
C. Is also called the Cori cycle 
D. Produces most of the water made in humans
• The Krebs Cycle begins when pytuvic acid 
produced by glycolsis enters the 
A. cytosol 
B. air 
C. mitochondrion 
D. nuclear
• During the fasting state, the release of fatty 
acids from adipose tissue is increased. At least 
part of the signal for this release is carried by 
A. insulin from beta-cells of the pancreas 
B. epinephrine from alpha-cells of the pancreas 
C. epinephrine from the adrenal medulla 
D. glucagon from the adrenal medulla
• In aerobic organisms growing in the 
presence of oxygen, the NADH produced by 
glycolysis ultimately donates its high-energy 
electrons to . 
A. electron transport chains in the 
mitochondria 
B. ATP 
C. pyruvate 
D. glucose
• Cellular respiration takes place mostly 
in: 
A. chloroplasts 
B. ribosomes 
C. nucleus 
D. mitochondria
• The main purpose of the electron transport 
chain is to: 
A. Use high energy electrons from other 
cycles to convert ADP into ATP 
B. Maintain a stable balance of high energy 
electrons 
C. Constantly distribute electrons throughout 
the cell 
D. Tell the cell when glycolysis should stop or 
start
• Oxidative phosphorylation: 
A. Is anaerobic 
B. Requires AMP 
C. Requires the electron transport system 
D. Is not dependent upon development of 
a proton gradient
• Where are the proteins of the electron 
transport chain located? 
A. cytosol 
B. mitochondrial outer membrane 
C. mitochondrial inner membrane 
D. mitochondrial matrix
• The ATP synthase responsible for most of the 
ATP synthesis in the body is located: 
A. On the outer side of the outer mitochondria 
membrane 
B. On the inner side of the outer mitochondria 
membrane 
C. On the outer side of the inner mitochondria 
membrane 
D. On the inner side of the inner mitochondria 
membrane
• In the electron transport chain, the final 
electron acceptor is 
A. oxygen 
B. a molecule of carbon dioxide 
C. a molecule of water 
D. ADP
• A mitochondrion is producing ATP at a constant 
rate and, then, a chemical uncoupler is added. 
Compared to before the uncoupler was added: 
A. Less heat would be produced 
B. Less water would be produced 
C. More NADH would be oxidized 
D. The proton gradient across the membrane 
would be increased
Matrix 
H+ 
+ NADH NAD+ 
+ 2H+ 2H+ 
+ ½ O2 H2O 
2 e- 
I Q III IV 
cyt c 
uncoupler 
4H+ 4H+ 2H+ H+ 
Intermembrane Space 
With uncoupler present, there is no DpH or DY. 
  DG for H+ ejection is zero 
  DG for e- transfer coupled to H+ ejection is maximal 
(spontaneous). 
Respiration proceeds in the presence of an uncoupler, 
whether or not ADP is present.
• A direct inhibitor of the ATP synthase (i.e. 
the ability to make ATP) in the presence of 
active electron transport: 
• A. would increase the membrane potential. 
• B would decrease the membrane potential. 
• C would increase electron transport rates 
• D would decrease the pH gradient.
• During chemiosmosis, 
A. energy is released as H+ ions move across 
mitochondrial membranes 
B. H+ do NOT play any role in the production of ATP 
molecules 
C. a concentration gradient is generated when large 
numbers of H+ ions are passively transported from the 
matrix of the mitochondrion to the mitochondrion's 
intermembrane space 
D. ATP is synthesized when H+ ions move through a 
channel in ATP synthase
• The chemiosmotic theory holds all of the following 
EXCEPT: 
A. The cytosol has a higher pH than the matrix 
B. In the absence of a proton motive force, ATP will not 
be synthesized 
C. The electrochemical potential comes from both the 
electrical potential and the proton concentration gradient 
D. Electrons are passed from one carrier to the next as 
protons are pumped across the inner mitochondrial 
membrane
• During REDOX reactions in cellular 
respiration, glucose undergoes _____ 
while oxygen undergoes______ 
A. reduction ..... oxidation 
B. oxidation ..... reduction 
C. no change ..... oxidation 
D. none of the above
• Anemia, hemorrhage, and chronic obstructive pulmonary disease 
can all cause metabolic acidosis. The best explanation is that the 
lack of oxygen causes 
A. a decrease in insulin that, in turn, increases anaerobic glycolysis 
in the brain 
B. a decrease in oxidative phosphorylation so the cells have to rely 
upon anaerobic glycolysis 
C. a decrease in the removal of CO2 from the blood. The resulting 
decrease in pH causes an increase in glycolysis in most cells 
D. an increase in glycolysis in red blood cells
• Hydrolysis of a triglyceride produces 
A. many amino acids 
B. different types of nucleotides 
C. fatty acids and glycerol 
D. monosaccharides
• Free fatty acids are able to travel from 
adipose tissue to muscle or liver 
A. As independent water soluble 
compounds in the blood 
B. By using receptors on red blood cells 
C. Bound to serum proteins 
D. By using enzymes that modify them
• When the concentration of epinephrine or glucagon is 
high, they bind to receptors on adipose cell membrane 
and all of the following can be expected to occur 
EXCEPT 
A. Triacylglycerol is hydrolyzed to free fatty acids and 
glycerol 
B. Free fatty acids are carried to most tissues of the 
body by albumin 
C. Fatty acids are activated, enter the mitochondria, and 
are oxidized by β-oxidation and the TCA cycle 
D. Increased β-oxidation increases glycolysis in resting 
muscle
Amino acid metabolism
Sample question 
• The site of amino acid catabolism is the: 
A. Stomach 
B. Small intestine 
C. Large intestine 
D. Liver
Sample question 
• The first step in the catabolism of most amino 
acids is 
• A. Removal of carboxylate groups 
• B. Enzymatic hydrolysis of peptide bonds 
• C. Removal of the amino group 
• D. Zymogen cleavage
Sample question 
Which of the following is true of urea? 
• A. more toxic to human cells than ammonia 
• B. the primary nitrogenous waste products of 
humans. 
• C. insoluble in water 
• D. the primary nitrogenous waste product of 
most aquatic invertebrates
Sample question 
A glucogenic amino acid is one which is 
degraded to 
• A. keto-sugars 
• B. either acetyl CoA or acetoacetyl CoA 
• C. pyruvate or citric acid cycle 
intermediates 
• D. none of the above
Sample question 
Transamination is the process where 
• A. carboxyl group is transferred from amino 
acid 
• B. α-amino group is removed from the amino 
acid 
• C. polymerization of amino acid takes place 
• D. none of the above
Sample question 
Transamination is the transfer of an amino 
• A. acid to a carboxylic acid plus ammonia 
• B. group from an amino acid to a keto acid 
• C. acid to a keto acid plus ammonia 
• D. group from an amino acid to a carboxylic 
acid
Nucleic acid metabolism
Sample Question 
• In inherited deficiency of hypoxanthine 
guanine phosphoribosyl transferase 
(A) De novo synthesis of purine nucleotides is 
decreased 
(B) Salvage of purines is decreased 
(C) Salvage of purines is increased 
(D) Synthesis of uric acid is decreased
Sample Question 
• Which of the following is a required 
substrate for purine biosynthesis ? 
(A) 5- methyl thymidine 
(B) Ribose phosphate 
(C) PRPP 
(D) 5-Fluoro uracil
Sample Question 
• The conversion of Inosine mono phosphate 
(A) To Adenosine mono phosphate (AMP) is 
inhibited by Guanosine mono phosphate (GMP) 
(B) To AMP requires uridine mono phosphate 
(UMP) 
(C) To GMP requires GMP kinase 
(D) To GMP requires Glutamine
HN 
N 
O 
N N 
Ribose-P 
Aspartate + GTP 
N 
N 
NH 
N N 
Ribose-P 
COO- 
-OOC 
HN 
N 
O 
N N 
Ribose-P 
O 
H 
Adenylosuccinate xanthine monophosphate 
XMP 
IMP 
IMP dehydrogenase 
NAD+ 
NADH 
A.S. 
synthetase 
GDP 
N 
N 
NH2 
N N 
Ribose-P 
HN 
N 
O 
N N 
H2N 
Ribose-P 
A.S. 
lyase 
fumarate 
glutamine + ATP 
Glutamate + AMP 
+ PPi 
AMP GMP 
Synthesis of adenine 
and guanine nucleotides 
IMP to AMP and GMP 
• Glutamine, 
NAD, ATP used 
in GMP 
production 
• Aspartate, GTP 
used AMP 
production
DNA replication
Sample questions 
• Both strands of DNA serve as 
templates concurrently in 
• A. replication 
• B. excision repair 
• C. mismatch repair 
• D. none of these
• Proofreading activity to maintain the fidelity of 
DNA synthesis 
• A. occurs after the synthesis has been completed 
• B. is a function of the 3'-5' exonuclease activity of the 
DNA polymerases 
• C. requires the presence of an enzyme separate from 
the DNA polymerases 
• D. occurs in prokaryotes but not eukaryotes
• Which of the following repairs nicked DNA by forming a 
phosphodiester bond between adjacent nucleotides? 
• A. Helicase 
• B. DNA gyrase 
• C. Topoisomerases 
• D. DNA ligase
• The replication of chromosomes by eukaryotes occurs in 
a relatively short period of time because 
• A. the eukaryotes have more amount of DNA for 
replication 
• B. the eukaryotic replication machinery is 1000 times 
faster than the prokaryotes 
• C. each chromosome contains multiple replicons 
• D. eukaryotic DNA is always single stranded
• During which of the following process a new 
copy of a DNA molecule is precisely 
synthesized? 
• A. Trasformation 
• B. Transcription 
• C. Translation 
• D. Replication
• Which of the following enzyme adds 
complementary bases during replication? 
• A. Helicase 
• B. Synthesase 
• C. Replicase 
• D. Polymerase
• Which of the following enzymes unwind short stretches 
of DNA helix immediately ahead of a replication fork? 
• A. DNA polymerases 
• B. Helicases 
• C. Single-stranded binding proteins 
• D. Topoisomerases
• Which DNA polymerase removes RNA primers 
in DNA synthesis? 
• A. Polymerase I 
• B. Polymerase II 
• C. Polymerase III 
• D. none of these
DNA polymerases are specialized for different roles in 
the cell
• Enzyme, responsible for proofreading base 
pairing is 
• A. DNA polymerase 
• B. Telomerase 
• C. Primase 
• D. DNA ligase
• DNA helicase is used to 
• A. unwind the double helix 
• B. interact the double helix closely 
• C. break a phosphodiester bond in DNA strand 
• D. none of the above
• The synthesis of DNA by DNA polymerase occurs in the 
• A. 3' to 5' direction 
• B. 5' to 5' direction 
• C. 5' to 3' direction 
• D. 3' to 3' direction
• The 5' and 3' numbers are related to the 
• A. length of the DNA strand 
• B. carbon number in sugar 
• C. the number of phosphates 
• D. the base pair rule
• What is the main damaging effect of UV 
radiation on DNA? 
• A. Depurination 
• B. Formation of thymine dimers 
• C. Single strand break 
• D. Dehydration
What is the function of DNA polymerase? 
Explain how a DNA molecule contains the 
information necessary to produce copies of itself. 
• DNA polymerase is an enzyme that catalyzes the 
reaction that adds nucleotides to a growing DNA 
strand while replication occurs. This enzyme also 
has a role in repairing errors in DNA molecules. 
• Each strand of a DNA molecule serves as a template 
for the synthesis of a complementary DNA strand 
using base pair relationships. This makes it possible 
to produce an exact copy of a DNA molecule.
Transcription
Sample questions 
• Which of the following enzyme is used 
for synthesis of RNA under the direction 
of DNA? 
• A. RNA polymerase 
• B. DNA ligase 
• C. DNA polymerase 
• D. RNA ligase
• Which of the following is a product of 
transcription? 
• A. mRNA 
• B. tRNA 
• C. rRNA 
• D. all of these
• Recognition/binding site of RNA 
polymerase is called 
• A. receptor 
• B. promoter 
• C. facilitator 
• D. terminator
• An mRNA transcript of a gene 
contains 
• A. a start codon 
• B. a stop codon 
• C. a terminator 
• D. all of these
• The components found in all prokaryotic 
transcription terminators is 
• A. a poly-U region 
• B. Rho factor 
• C. a hairpin structure 
• D. none of these
• Where in the cell is the DNA transcribed into 
mRNA? 
• A.Cytoplasm 
• B.Nucleus 
• C.Golgi 
• D.Cell cytoskeleton
• Which of the following does NOT happen during hnRNA 
processing? 
• A. Introns are spliced out. 
• B. A 7-methylguanosine cap is added to the 5' end of the RNA. 
• C. A poly A tail is added. 
• D. Ribosomes bind and begin translation.
• Since the two strands of the DNA molecule are 
complementary, for any given gene: 
• A. The RNA polymerase can bind to either strand. 
• B. Only one strand actually carries the genetic code for a 
particular gene. 
• C. Each gene possesses an exact replica so that no 
mutation occurs. 
• D. A gene transcribed in the 5’ to 3’ direction on one 
strand can be transcribed in the 3’ to 5’ direction on the 
other strand.
Translation
Sample questions 
• The site of protein synthesis is 
• A. Ribosome 
• B. Nucleus 
• C. Endoplasmic reticulum 
• D. Chromosome
Sample questions 
• The structure in a bacterium that 
indicates an active site for protein 
synthesis is 
• A. a chromosome. 
• B. a cell membrane, 
• C. a flagellum. 
• D. a polysome.
Sample questions 
• Which of the following is not 
necessary for protein synthesis to 
occur, once transcription is 
completed? 
• A. tRNA 
• B. Ribosomes 
• C. mRNA 
• D. DNA
Sample questions 
• During the process of translation: 
• A. the peptide is ‘passed’ from the tRNA in the P-site to the tRNA in 
the A-site. 
• B. incoming tRNAs must first bind to the E-site. 
• C. initiation begins with the binding of the ribosomal SSU to the 
poly-A tail of the mRNA. 
• D. the mRNA is translated by one ribosome at a time.
• The nucleolus of the nucleus is the site 
where: 
• A. RNA processing occurs 
• B. rRNA is transcribed and ribosomal subunits are 
assembled 
• C. tRNA are charged with amino acids 
• D. mRNA is translated into protein
Ribosome Assembly: takes place largely in a specialized domain of 
the nucleus, the nucleolus
• The ribosomes are composed of 
• A. proteins 
• B. RNA 
• C. both (a) and (b) 
• D. lipids
• Which is required for protein synthesis? 
• A. tRNA 
• B. mRNA 
• C. rRNA 
• D. All of these
• In the genetic code there are: 
• A. more tRNAs than codons. 
• B. more codons than amino acids. 
• C. more nucleotides than codons. 
• D. the same number of codons and amino 
acids
• he anticodon of tRNA 
• A. binds to rRNA 
• B. binds to an amino acid 
• C. binds to the Shine Dalgarno sequence 
• D. binds to an mRNA codon
• Initiation of eukaryotic translation begins when 
the: 
• A. large and small subunits link together, then bind to 
the mRNA. 
• B. ribosomal small subunit holding an initiator tRNA 
binds to the 5’ end of mRNA. 
• C. ribosome binds to of the start codon and an initiator 
tRNA enters the ribosome. 
• D. initiator tRNA binds to the start codon, followed by 
binding of the ribosome large subunit.
• On the ribosome, mRNA binds 
• A. between the subunits 
• B. to the large subunit 
• C. to the small subunit 
• D. none of these
In addition to the APE sites there is an mRNA binding groove 
that holds onto the message being translated
• The peptidyl transferase reaction 
occurs 
• A. on the large subunit 
• B. on the small subunit 
• C. between the subunit 
• D. none of these
• Ribosomes select the correct tRNAs 
• A. based on the aminoacyl group 
• B. solely on the basis of their anticodons 
• C. depending on their abundance in the 
cytosol 
• D. with the least abundant anticodons
• Which of the following amino acid 
starts all proteins synthesis? 
• A. Glycine 
• B. Proline 
• C. Thymine 
• D. Methionine
• The growing polypeptide chain is released 
from the ribosomes when 
• A. a chain terminating codon is reached 
• B. a chain terminating tRNA binds to the ribosome 
• C. the 7-methyl guanosine cap is reached 
• D. the poly A tail is reached
What is a gene? 
• A gene is a region of DNA whose final product is 
either a polypeptide or an RNA molecule
Gene regulation
Sample questions 
• The lac repressor is a 
• A. carbohydrate. 
• B. DNA molecule. 
• C. RNA molecule. 
• D. protein molecule.
• What would be the effect of a mutation in the 
operator that blocked the lac repressor binding? 
• A. The genes would be inducible by lactose. 
• B. The lacZYA genes would be expressed 
constitutively. 
• C. The lacZYA genes would not be expressed. 
• D. The lacZYA genes would be repressed by lactose.
• A regulatory site within the leader sequence of 
the tryptophan operon that controls this operon 
by diminishing transcription is called: 
• A.operator 
• B.upregulator 
• C.repressor 
• D.transcriptor
• Which level of primary control in eukaryotic 
gene activity involves processing early RNA 
transcripts to mRNA and control of the rate at 
which mRNA leaves the nucleus? 
• A. transcriptional control 
• B. translational control 
• C. posttranscriptional control 
• D. posttranslational control
• An enhancer site is 
• A. part of an operon. 
• B. found only in prokaryotes. 
• C. located at a distance from the gene it 
affects. 
• D. an attachment site for RNA 
polymerase.
Cell growth and carcinogenesis
Sample questions 
• The event(s) which does not occur during 
interphase, is/are 
• A. Chromatin condenses 
• B. Protein Synthesis 
• C. Organelles replication 
• D. DNA replication
The Cell 
Cycle 
• 2 major 
phases 
– Interphase 
– Mitosis
• At the center of the cell cycle control 
system is Cdk, a protein that 
• A. is phosphorylated to become active 
• B. binds to different cyclins 
• C. is only active during mitosis 
• D. manufactures growth factors
Sample questions 
• An oncogene is 
• A. a viral gene with no relation to the host cell's 
genes. 
• B. a mutated form of a proto-oncogene. 
• C. a bacterial gene that causes cancer in the 
host. 
• D. a gene that turns off cellular reproduction.
Questions that have been reviewed
The complementary sequence in the 
standard 5’ 3’ notation for GATCAA 
is _______ 
• TTGATC
List at least 3 non-covalent 
interactions in the biomolecules 
• van der Waals 
• Hydrogen bonds 
• Ionic bonds 
• Hydrophobic interactions
Explain the hydrophobic interactions 
• Hydrophobic interactions minimize 
interactions of non-polar components with 
aqueous solvent.
How are proteins separated by 
electrophoresis? 
• The separation of proteins is done by 
charge. pH is kept higher then the 
isoelectric pH (pI). So, the proteins will 
have negative charge and so the proteins 
will move towards the positive electrode.
Explain the definition of domain of proteins. 
• FFuunnddaammeennttaall ffuunnccttiioonnaall && tthhrreeee 
ddiimmeennssiioonnaall ssttrruuccttuurraall uunniittss ooff pprrootteeiinnss..
What is the function of chaperones in 
protein folding? List at least one role. 
• AAssssiisstt ffoollddiinngg 
• PPrrootteecctt aggregation 
• SSoommee ttiimmeess kkeeeepp pprrootteeiinn uunnffoollddeedd uunnttiill 
ssyynntthheessiiss iiss ccoommpplleettee..
Explain the difference between reversible denaturation and 
irreversible denaturation of proteins. 
• Some proteins can refold upon removal of 
denaturant. Other can’t refold upon the removal 
of denaturant.
Molecules contain both a positive and a 
negative charged functional group is 
called _____ 
• zwitterion
Hemoglobin is an allosteric protein that 
can exist in two states: R (relaxed) and 
T (taut). ____ state binds oxygen 
tighter. 
• R (relaxed)
The change in oxygen affinity with pH is known as 
the Bohr effect. Hemoglobin oxygen affinity is ____ 
(increased/decreased) as the acidity increases. 
• Reduced or decreased
Proteins that recognize and bind to a 
particular antigen with very high 
specificity belong to a group of serum 
proteins called ______. 
• Immunoglobulins or antibodies
What is the shape of the oxygen hemoglobin 
dissociation curve? 
How does the shape of the curve relate to 
the cooperative binding of O2? 
• Sigmoid or sigmoidal curve 
• The small change of oxygen partial 
pressure results in a greater change of 
the hemoglobin binding affinity to oxygen.
How does the shape of oxygen–hemoglobin 
dissociation curve influence loading of 
oxygen at the lung and unloading of oxygen 
at the tissue level? 
• There are a high oxygen partial pressure 
in the lung and a low oxygen partial 
pressure in the other tissues. At high 
oxygen pressure, the hemoglobin tends to 
be saturated with oxygen while, at low 
oxygen pressure hemoglobin tends to 
unload all the oxygen molecules.
List at least 3 factors that influence the 
binding of hemoglobin to oxygen. 
• carbon dioxide or CO2 
• pH or acidity 
• Oxidative state of Fe in the heme group 
• 2,3-DPG or 2,3-BPG 
• Carbon monoxide or CO
_____ are long polymers of nucleotides. 
• Nucleic acids
The maximal UV absorbance of nucleic 
acids and proteins are at the wavelength of 
___ nm and ___ nm, respectively. 
• 260, 280
The sugar groups in the nucleic acids are 
___ (D/L) ribose while the residues in the 
protein are ___ (D/L) amino acids. 
• D, L
Polymer of nucleotides linked in a 
direction from ribose carbon ___ (3’/5’) 
to carbon ___ (3’/5’) by ______bonds. 
• 5’, 3’, phosphodiester
List at least 3 types of RNA molecules 
in the biological system. 
• ribosomal RNA or rRNA 
• messenger RNA or mRNA 
• transfer RNA or tRNA 
• microRNA or miRNA 
• small RNA or siRNA 
• long non-coding RNA 
• short non-coding RNA
Besides hydrophobic interactions, hydrogen 
bonding, and electrostatic interactions, 
nucleic acids have one more type of 
noncovalent interaction that is called ____. 
• Stacking interactions or base stacking 
(interactions between stacked bases)
What is DNA melting temperature? 
• the temperature at which a DNA double 
helix dissociates into single strands
What is the purpose of using the polymerase 
chain reaction (PCR) in diagnosis or research? 
• to rapidly amplify sequences of DNA
In the nucleosome, DNA wrapped 
around an octamer protein complex that 
are called ____. 
• histone
DNA binding proteins bind DNA in two ways: 
sequence-specific binding and non-sequence 
specific binding. Please list two example of non-sequence 
specific binding proteins. 
• Single-stranded nucleic acid binding 
proteins (SSB) 
• Exonucleases, RNase, or DNase 
• RNA polymerases or DNA polymerases 
• Topoisomerases
Define the enzyme active site. 
• The active site of an enzyme represents 
as the small region at which the substrate 
(s) binds and participates in the catalysis
Feedback Inhibition is a type of allosteric 
regulation for enzyme. When does feedback 
inhibition occur? 
• This occurs when an end-product of a 
pathway accumulates as the metabolic 
demand for it declines.
For every molecule of glucose that enters 
glycolysis, there is an initial investment of 2 
molecules of ____ before the subsequent 
generation of ____ . 
• ATP, ATP
What is the purpose of glucagon? 
• It slows down glycolysis when blood sugar 
is low and stimulates the formation of 
more glucose.
An enzyme that catalyzes the 
phosphorylation of a molecule using ATP is 
called ____ 
• Kinase
Name two molecules that carries electrons 
from glycolysis and Krebs Cycle to the 
electron transport system. 
• NADH and FADH2
Phosphofructokinase-1 (PFK-1) is an enzyme in glycolysis. 
It’s activity is controlled by a complex allosteric regulation. 
What is the function of AMP in the PFK-1 regulation? 
• AMP allosterically activates PFK-1
There are three irreversible reactions in the 
glycolysis. What are the corresponding 
enzymes that catalyze those reactions? 
• Hexokinase or Glucokinase 
• Phosphofructokinase 1 or PFK-1 
• Pyruvate Kinase
Hexokinase is allosterically inhibited by its product Glucose 
6 phosphate. The hexokinase in the liver is called 
glucokinase. However, glucokinase is not subject to product 
inhibition by glucose-6-phosphate. What the benefit of this 
characteristics of glucokinase? 
• Liver will take up & phosphorylate glucose 
even when liver glucose-6-phosphate 
concentration is high.
During the Cori cycle, _____ is transported 
to the liver to regenerate glucose which is 
returned to muscle tissue. 
• Lactic acid or lactate
Insulin is produced when blood glucose is 
high. How does insulin regulate the 
transcription of the glycolysis enzyme in liver, 
glucokinase? 
• Insulin activates of transcription of 
Glucokinase in liver.
In the liver, the most important coordinating modulator is fructose 2,6- 
bisphophate (F2,6BP). It is formed from F6P by the enzyme domain, 
phosphofructokinase-2 (PFK-2), and broken down by the same enzyme, 
but at a different domain called fructose 2,6-bisphosphatase (FBPase- 
2). How does the balance of PFK-2 to FBPase-2 activity controlled by 
glucagon? 
• Glucagon causes the enzyme phosphorylation. 
Phosphorylation of the enzyme results in the 
inactivation of the phosphofructokinase-2 activity 
and activation of the fructose-2,6- 
bisphosphatase activity.
The last product of glycolysis is ____ while 
the first reactant of Krebs cycle is ____. 
• Pyruvate, Acetyl Co-A
Briefly explain the Cori cycle which is a 
linked metabolic pathways. 
• The glucose can enter the blood and be 
carried to muscles. 
• Lactic acid is produced by anaerobic 
glycolysis in the muscles 
• The lactic acid is sent in the blood to the 
liver which can convert it back to glucose 
through gluconeogenesis.
What is epinephrine’s role in glycogen 
and glucose metabolism? 
• Epinephrine markedly stimulates glycogen 
breakdown and glycolysis.
Palmitic acid, CH3(CH2)14COOH, can 
maximally yield ____ acetyl-CoAs 
through ____ cycles of beta-oxidation. 
• Eight, seven
Why can acetone be detected on 
breath of diabetic patients? 
• Acetone breath in diabetics is caused by an 
excess production of ketone bodies. 
• Glucose is abundant in blood, but uptake by 
cells in muscle, liver, and adipose cells is low. 
Cells, metabolically starved, turn to 
gluconeogenesis and fat/protein catabolism 
• However, due to excess gluconeogenesis, 
oxaloacetate is low, so acetyl-CoA from 
fat/protein catabolism does not go to TCA, but 
rather to ketone body production.
High cholesterol diet leads to ____ 
(promotion/repression) of LDL receptor synthesis. 
• repression
Chylomicrons are vesicles found in the blood and lymphatic 
fluid where they serve to transport lipid from the intestine to 
the liver and to adipose tissue. Of what are the chylomicrons 
composed? List at least 3 components. 
• Triglycerides 
• Cholesterols 
• lipoproteins 
• phospholipids 
• Cholesteryl ester
What is the effect of epinephrine and 
glucagon on triglyceride metabolism? 
• Epinephrine and glucagon trigger the 
mobilization of stored triglycerides
What is oxidative phosphorylation? 
• Answer1: Oxidative phosphorylation 
transfers energy from NADH to ATP. (via 
chemiosmosis) 
• Answer2: Oxidative phosphorylation is the 
process of converting this high redox 
potential into energy-rich ATP molecules.
Oxidative phosphorylation is accomplished 
via two separate systems in the 
mitochondrion. What are those two systems? 
• Electron transport chain system and ATP 
synthesis system.
ATP synthesis is driven by proton motive 
force. What are the two types of gradient 
associated with proton motive force? 
• a proton gradient or pH gradient 
• a electrical gradient or ion gradient
Metabolism of amino acids differs, but all of 
them require the removal of amino groups. 
What are the two types of reactions to 
remove amino groups? 
• Transamination 
• Deamination
Disposal of ammonia from amino acid metabolism 
as _____ in most tissues especially in the brain 
and kidneys, as _____ in the liver, and as _____ 
in the skeletal muscles. 
• Glutamine, urea, alanine
Based on the catabolic fates of carbon 
skeleton of amino acids, the amino 
acids can be classified as ____ or 
_____. 
• Glucogenic, ketogenic
Dietary nucleotides _____ (do/do not) 
contribute energy as an energy source 
material and _____ (are/are not) 
incorporated into RNA or DNA. 
• Do not, are not
The purine nucleotides are synthesized via 
two pathways in the body. One is ____ 
synthesis pathway while the other is ____ 
pathway. 
• De novo, salvage
The purine synthesis is _____ by PRPP, 
_____ by IMP, _____ by AMP, and _____by 
GMP. Fill the blank with activated or 
inhibited. 
• Activated, Inhibited, 
Inhibited, Inhibited,
What are the carbohydrate and fat 
metabolic events occurred in liver 
during fasting? 
• The liver first starts glycogen degradation, 
then gluconeogenesis to maintain blood 
glucose levels. 
• The fatty acid oxidation and ketone body 
production are increased.
Insulin promotes the translocation of 
______ to the plasma membrane. 
• GLUT or glucose transporter
Why do we say that DNA replication is 
semiconservative? 
• The new strands composed of one original 
strand and one daughter strand
DNA polymerases cannot initiate synthesis of a 
polynucleotide; they can only add nucleotides to 
the 3’ end. Therefore, a short _____ is required to 
initiate nucleotide synthesis. 
• RNA primer
Eukaryotic chromosomal DNA molecules have 
special nucleotide sequences at their ends called 
______. 
• telomeres
Why is DNA replication semi-discontinuous? 
• DNA strands are antiparallel. And, 
replication process obeys the principle that 
DNA is synthesized from the 5´ end to the 
3´end. 
• Leading strand synthesized continuously 
while lagging strand synthesized 
discontinuously
List at least 3 differences between 
replication and transcription. 
replication transcription 
template double strands single strand 
substrate dNTP NTP 
primer yes no 
Enzyme DNA polymerase RNA polymerase 
product dsDNA ssRNA 
base pair A-T, G-C A-U, T-A, G-C 
The whole genome of DNA needs to be replicated, but only small 
portion of genome is transcribed
During transcription, one of the DNA strands 
called ______ strand is the strand from which 
the RNA is actually transcribed. The other 
strand called _____ strand is the strand whose 
base sequence specifies the amino acid 
sequence of the encoded protein. 
• Template, coding
What is asymmetric transcription? 
• Only the template strand is used for the transcription, but 
the coding strand is not. 
• The transcription direction on different strands is 
opposite. 
5' 
3' 
3' 
5'
The mRNA start codon is ___ in 
most cases. 
• AUG
Deoxyribonucleotides are formed from 
their corresponding _____. 
• ribonucleotides
Explain mRNA splicing 
• During splicing, introns are removed from 
the strand, and the exons that remain are 
assembled into a finished strand of mRNA 
that is ready for translation.
What is the consequence of 
frameshift mutation? 
• Frameshift mutations result in all 
subsequent reading frames (codons) 
being shifted by one or two nucleotides. 
These shifted frames will code for different 
amino acids than before, and will result in 
the creation of a malfunctioning protein.
The GUU  GUA transition still codes for 
Val and it therefore called to be ______ 
mutation. 
• nonsense
The insertion or deletion of a nucleotide 
into a gene results in a _____ mutation. 
• frameshift
An incoming aminoacyl-tRNA enters 
the ribosome at the ___ site. 
• A
____ are synthesized as inactive precursors 
that require proteolysis for activation. 
• zymogen or proenzyme
In the operon system, tryptophan acts 
as a ____ by binding the trp repressor. 
• Co-repressor

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Questions of biochemistry with answers of all chapter

  • 1. What are the chemical elements that form most of living biological matter? The chemical elements that form most of the molecules of living beings are oxygen (O), carbon (C), hydrogen (H) and nitrogen (N).
  • 2. • Glucose and fructose are examples of A. double sugars B. disaccharides C. single sugars D. polysaccharides
  • 3. • What are described as the "building blocks of Protein"? A. Fiber B. Lipids C. Amino Acids D. Nutrients
  • 4. • (CH2O)n is the molecular formula for which type of macromolecules? A. Proteins B. Lipids C. Carbohydrates D. Nucleic Acid
  • 5. • Which macromolecule does not dissolve in water? A. proteins B. lipids C. carbohydrates D. nucleic acids
  • 6. • What type of organic substances are fats? A. nucleic acid B. carbohydrate C. protein D. lipids
  • 7. • What are the monomers of lipids? A. Amino acids B. Simple sugars C. Fatty acids and glycerol D. Nucleic acids
  • 8. • Which of the following is a polymer? A. nucleic acid B. fatty acid C. Amino acid D. Glycerol
  • 9. • Proteins are ____ made of amino acid ____ . A. monomers; polymers B. polymers; polypeptides C. polymers; monomers D. monomers; molecules
  • 10. • Which of the following is NOT a polysaccharide? A. Glycogen B. Starch C. Sucrose D. Cellulose
  • 11. • What are used in animals as a source of quick energy that can be stored in the liver and muscles ? A. Proteins B. Nucleic acids C. Carbohydrates D. Lipids
  • 12. • Fats that have fatty acids with only single covalent bonds in their carbon skeletons are A. saturated B. unsaturated C. found in plants instead of animals D. liquid at room temperature
  • 13. • Sugars, starches, and cellulose belong to which major class of biological molecules? A. Nucleic acids B. carbohydrates C. lipids D. polypeptides
  • 14. • Plants like sugar cane and sugar beets store the energy as simple sugars. Other plants, like corn and potatoes, store the energy as more complex sugars called? A. carbohydrates B. calories C. starches D. cellulose
  • 15. • This biological macromolecule is responsible for controlling the activity of the cell, and it stores and transports genetic information. A. Carbohydrate B. Nucleic acid C. Water D. Glucose
  • 16. • In this type of structure, most of carbonyl groups of peptide bonds forms a hydrogen bond with the amide nitrogen of another peptide bond four amino acids further down the polypeptide chain: A. Alpha-helix B. Beta-sheet C. Beta-turn D. Quaternary
  • 17. • Lipids are used by the body to perform all of the following functions EXCEPT: A. membrane structural material. B. enzyme action. C. insulation. D. a rich energy source.
  • 18. • What is the constitutional unit of proteins? • What is the primary structure of a protein? • The constitutional units of proteins are the amino acids. • The primary protein structure is the linear sequence of amino acids that form the molecule.
  • 19. What is the secondary structure of a protein? • The secondary protein structure is generated by the manner its amino acids interact through the inter-residue bond. These interactions create a spatial conformation of the polypeptide filament. The two most studied secondary conformations of proteins are the alpha-helix and the beta-sheet.
  • 20. • The isoelectric point of an amino acid is defined as the pH A. where the molecule carries no electric charge B. where the carboxyl group is uncharged C. where the amino group is uncharged D. of maximum electrolytic mobility
  • 21. • When the amino acid alanine (R-group is CH3) is added to a solution with a pH of 7.3, alanine becomes A. a cation Isoelectric B. nonpolar point of C. a zwitterions alanine is D. an anion 6.00
  • 22. • The term “SALTING IN” refers to? A. Changes in an amino acid’s isoelectric point. B. Increasing the solubility of a protein in solution by adding ions. C. The use of a liquid bridge in an electrochemical cell. D. The ionization of a strong acid.
  • 23. Salting Out (by solubility) • Most proteins are less soluble at high salt concentrations, an effect called salting out. • The salt concentration at which a protein precipitates differs from one protein to another. Hence, salting out can be used to fractionate proteins. • Dialysis can be used to remove the salt if necessary.
  • 24. • The local spatial arrangement of a polypeptide’s backbone atoms without regard to the conformation of its side chains can be called as A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure
  • 25. • Which of the following amino acids are more likely to be found in a protein’s interior away from aqueous solvent molecules? A. Val, Leu, Ile, Met, and Phe B. Ser, Thr, Asn, Gln, and Tyr C. Arg, His, Lys, Asp, and Glu D. All of the above.
  • 26. • Which of the following is (are) true of b- turns in proteins? A. It is a 180º turn of four amino acids. B. Glycine and proline are frequently found there. C. Are used as connecting turns of a- helix D. All of the above.
  • 27. • The primary stabilizing force of protein secondary structure is: • A Ionic bonds. • B Covalent bonds. • C Van der Waals forces. • D Hydrogen bonds
  • 28. • Two types of b-pleated sheets can be called: • A parallel and antiparallel • B left-handed and right-handed. • C Fand Y • D α and β
  • 29. • Which of the following is NOT a characteristic of a globular protein? • A Polypeptide chain in extended, long sheets • B Polypeptide chains are folded in a spherical shape. • C Contains several types of secondary structure • D Typical for regulatory proteins.
  • 30. • Which of the following statements regarding ligand binding is NOT correct? A. Some proteins require ligands in order to perform their function B. Enzymes with their attached ligands are called holoenzymes C. Ligands are synonymous with prosthetic groups D. The heme group on hemoglobin is an example of a tightly bound ligand
  • 31. • The alpha helix found in myoglobin can best be described as A. Primary structure B. Secondary structure C. Tertiary structure D. Motif structure
  • 32. • Some parts of a protein that have a specific chemical structure and function are called protein A. chemicals B. domains C. subunits D. enzymes
  • 33. • One of the following is NOT usually a force that helps to hold the monomer units of a quaternary protein together? A. Peptide bonds B. Disulfide bonds C. Salt bonds D. Hydrophobic interactions
  • 34. What is the quaternary structure of a protein? Do all proteins have quaternary structure? • The quaternary protein structure is the spatial conformation due to interactions among polypeptide chains that form the protein. • Only those proteins made of two or more polypeptide chains have quaternary structure.
  • 35. What is protein denaturation? Is there any change in the primary structure when a protein is denatured? What are some factors that can lead to protein denaturation? • Secondary, tertiary and quaternary structures of proteins are spatial structures. Denaturation is modification in any of these spatial structures that makes the protein deficient or biologically inactive. • After denaturation the primary protein structure is not affected. • Protein denaturation can be caused by temperature variation, pH change, changes in the concentration of surrounding solutes. Most proteins denature after certain elevation of temperature or when in very acid or very basic solutions.
  • 36. • Which of the following terms describes hemoglobin but not myoglobin? A. The protein contains hydrogen bonds B. The protein contains a hydrophobic pocket that contains heme C. Imidazole groups stabilize the ferrous ion D. The protein contains alpha and beta chains
  • 37. • Of the following states of hemoglobin (Hb), which is least likely to bind the next molecule of oxygen (O2)? A. Hb B. Hb (O2) C. Hb (O2)2 D. Hb (O2)3
  • 38. • If a person breathes into a paper bag, you would expect their blood CO2 to A. decrease and their blood pH to increase B. decrease and their blood pH to decrease C. increase and their blood pH to increase D. increase and their blood pH to decrease
  • 39. • The quaternary structure of a protein is A. the sequence of amino acids in the polypeptide B. the coiling or folding of the polypeptide C. the intertwining of two or more polypeptides D. the 3-dimensional appearance of the polypeptide
  • 40. • The action of disrupting the three-dimensional shape of a protein is termed A. dehydration B. denaturation C. deamination D. hydrolysis
  • 41. SSaammppllee qquueessttiioonnss • At a pH >pI of a given protein, that protein becomes ______, at the pH<pI of that same protein, it becomes _______. negatively charged (an anion) positively charged (a cation) The isoelectric point (pI) is the pH at which a particular molecule or surface carries no net electrical charge.
  • 42. SSaammppllee qquueessttiioonnss • What is the prosthetic group that hemoglobin and myoglobin's oxygen binding ability depend on? Heme • Define cooperativity relative to binding oxygen binding of oxygen at one site increases chances of binding oxygen at the other sites; loss of an oxygen at one site increases the chances of losing oxygen at the other sites • What are the two states of the hemoglobin quaternary structure? And what are their characteristics? T state = taut (deoxy form) R state = relaxed (oxygenated form)
  • 43. Sample questions • The imino acid found in protein structure • (a) Arginine • (b) Proline • (c) Histidine • (d) Lysin
  • 44. • The bonds in protein structure that are not broken on denaturation. • (a) Hydrogen bonds • (b) Peptide bonds • (c) lonic bond • (d) Disulfide bonds
  • 45. • Which of the following is not considered a pyrimidine? A. C B. T C. U D. G • What type of sugar is found in the nucleotides of DNA? A. deoxyribose B. ribose C. glucose D. none of the above
  • 46. • What is the role of hydrogen bonds in the structure if DNA? A. to code for proteins B. to synthesize proteins C. to separate the strands D. to connect the base pairs
  • 47. Which type of chemical bond maintains the pairing of each chain in the DNA molecule? • To form the DNA molecule, purine bases bind to pyrimidine bases by intermolecular bonds called hydrogen bonds. Hydrogen bonds occur when there is hydrogen near one of these electronegative elements: oxygen or nitrogen.
  • 48. Sample questions for the nucleic acid section Nucleoside is a pyrimidine or purine base • A.covalently bonded to a sugar • B.ionically bonded to a sugar • C.hydrogen bonded to a sugar • D.none of the above The sugar in RNA is ______ , the sugar in DNA is _____ • A.deoxyribose, ribose • B.ribose, deoxyribose • C.ribose, phosphate • D.ribose, uracil
  • 49. Sample questions for the nucleic acid section In gel electrophoresis, what fragments will move most quickly through a gel? • A.Large fragments • B.Small fragments • C.Large genome • D.None of these Nucleotide bases and aromatic amino acids absorb light respectively at • A.280 and 260 nm • B.260 and 280 nm • C.270 and 280 nm • D.260 and 270 nm
  • 50. Sample questions for the nucleic acid section Which of the following is found on RNA but not DNA? • A.Uracil • B.Deoxyribose • C.Phosphate • D.Adenine Which is true about the pairing of bases in the DNA molecule? • A. purines always pair with pyrimidines • B. a single ring base pairs with another single ring base • C. a double ring base pairs with another double ring base • D. purines pair with purines and pyrimidines with pyrimidines
  • 51. Sample questions for the nucleic acid section A messenger acid is 336 nucleotides long, including the initiator and termination codons. The maximum number of amino acids in the protein translated from this mRNA is: • A 999 • B 630 • C 330 • D 111 • E 110 With what mRNA codon would the tRNA in the diagram be able to form a codon-anticodon base pairing interaction? • A. 3'-AUG-5' • B. 3'-GUA-5' • C. 3'-CAU-5' • D. 3'-UAC-5' • E. 3'-UAG-5'
  • 52. Sample questions for the nucleic acid section • Of what units are nucleic acids constituted? What are the chemical entities that compose that unit? • What is the rule for the pairing of nitrogenous bases in the DNA molecule? And in the RNA? • For each of the following structures identify: the carbohydrate (ribose or deoxyribose)?; nucleoside or a nucleotide? DNA or a RNA system?
  • 53. Sample questions What is the function of enzymes within living systems? • A) structural elements • B) neurotransmitters • C) catalysts • D) hormones Enzymes have names that • A) always end in -ase • B) always end in -in • C) can end either in -in or -ase • D) can end in either -in or -ogen
  • 54. Sample questions The protein portion of a conjugated enzyme is called a(n) • A) apoenzyme. • B) coenzyme. • C) holoenzyme. • D) cofactor. Which of the following could be a component of a conjugated enzyme? • A) coenzyme • B) cofactor • C) apoenzyme • D) more than one correct response • E) no correct response
  • 55. Sample questions Enzyme cofactors that bind covalently at the active site of an enzyme are referred to as _________. • (a) cosubstrates. • (b) prosthetic groups. • (c) apoenzymes. • (d) vitamins
  • 56. Sample questions Which of the following statements concerning the effect of temperature change on an enzyme-catalyzed reaction is correct? • A) An increase in temperature can stop the reaction by denaturing the enzyme. • B) An increase in temperature can increase the reaction rate by increasing the speed at which molecules move. • C) An increase in temperature to the optimum temperature maximizes reaction rate. • D) more than one correct response • E) no correct response
  • 57. Sample questions • A catalyst can promote product formation during a chemical reaction by _____. • (a) lowering the activation energy barrier. • (b) stabilizing the transition state. • (c) positioning reactants in the correct orientation. • (d) bringing reactants together. • (e) all of the above Which of the following is characteristic of an enzyme catalyst? • (a) It positions reactants in the correct orientation. • (b) It lowers the activation energy barrier. • (c) It binds the transition state tighter than the substrate. • (d) all of the above
  • 58. Sample questions An enzyme active site is the location in the enzyme where • A) protein side groups are brought together by bending and folding to form a site for interactions with substrates • B) the catalyst interactions with the enzyme • C) catalyst molecules are generated • D) the substrate creates the catalyst molecules An enzyme active site is the location in an enzyme where substrate molecules • A) are generated. • B) become catalysts. • C) undergo change. • D) more than one correct response • E) no correct response
  • 59. • For the enzyme reaction A+ B = C + D, Delta Go' = + 1 kcal/mol. This reaction will proceed spontaneously in a forward direction if: A. The concentration of C is increased one-hundred fold B. The concentration of A is increased one-hundred fold C. The concentration of B is lowered one-hundred fold D. The concentration of both A and D are increased one-hundred fold
  • 60. • Which of the following statements about enzymes or their function is true? A. Enzymes do not alter the overall change in free energy for a reaction B. Enzymes are proteins whose three-dimensional form is key to their function C. Enzymes speed up reactions by lowering activation energy D. All of the above
  • 61. • What is the optimal temperature range for the majority of enzymes? A. 40-55 ℃ B. 35-40 ℃ C. 25-30 ℃ D. 15-20 ℃
  • 62. • An allosteric activator A. increases the binding affinity B. decreases the binding affinity C. stabilizes the R state of the protein D. both (a) and (c)
  • 63. • Reactants of an enzyme-catalyzed reaction are known as A. products B. substrates C. proteins D. complex
  • 64. • The location on an enzyme where binding occurs is known as the A. action point B. enzyme C. binding location D. active site
  • 65. • Enzymes catalyze reactions by A. Increasing the free energy of the system so that the change in free energy is positive B. Increasing the free energy of the substrate so that it is greater than the free energy of the product C. Changing the equilibrium constant for the reaction D. Decreasing the free energy of activation
  • 66. • An apoenzyme A. Includes non-protein compounds such as metal ions B. Consists of complex organic structures which may be classified as activation-transfer coenzymes or oxidation-reduction coenzymes C. Is the protein portion of the enzyme without the cofactors D. None of the above
  • 67. • NAD+, FAD, and FMN are all cofactors for: A. Oxidoreductases B. Transferases C. Hydrolases D. Ligases
  • 68. • At the end of a chemical reaction A. an enzyme's structure is altered B. an enzyme is detached from the product, has its original structure, and can catalyze more chemical reactions C. the enzyme loses its ablity to catallyze other chemical reactions D. the enzyme remains attached to the products
  • 69. Sample questions The rate of a second order reaction depends on the concentration of _________. • (a) one substrate • (b) two substrates • (c) three substrates • (d) none of the above
  • 70. Rate constants and reaction order Rate constant (k) measures how rapidly a reaction occurs k1 k-1 A B + C Rate (v, velocity) = (rate constant) (concentration of reactants) v= k1 [A] 1st order reaction (rate dependent on concentration of 1 reactant) v= k-1[B][C] 2nd order reaction (rate dependent on concentration of 2 reactants) Zero order reaction (rate is independent of reactant concentration)
  • 71. • On the following plot, N represents the curve for an allosteric enzyme with no allosteric activators or inhibitors added. If an allosteric activator was added, which curve would one obtain? A. Curve A B. Curve B C. Curve C D. Curve D
  • 72. • Which of the following statements about allosteric enzymes is CORRECT? A. The binding of substrate to any active site affects the other active sites B. The plot of initial velocity vs. substrate concentration is a straight line C. The Keq of the reaction is increased when allosteric activator is bound D. The enzymes contains only one polypeptide chain
  • 74. Sample questions Which of the following kinetic parameters best describes how well suited a specific compound functions as a substrate for a particular enzyme? • (a) Km • (b) Vmax • (c) kcat • (d) kcat/Km
  • 75. Short summary • Km  substrate specificity; substrate binding • kcat,  the turnover number • kcat/Km  the catalytic efficiency
  • 76. Sample questions The rate-determining step of Michaelis Menten kinetics is • A.the complex formation step • B.the complex dissociation step to produce product • C.the product formation step • D.Both (a)and(c)
  • 77. • A competitive inhibitor of an enzyme works by A. fitting into the enzyme's active site B. fitting into the allosteric site of the enzyme C. attaching itself to the substrate, thereby preventing the enzyme from making contact with substrate D. increasing the activation energy of the enzyme-catalyzed reaction
  • 78. • If an enzyme is described by the Michaelis- Menten equation, a competitive inhibitor will: A. decrease the Km and decrease the Vmax B. decrease the Km, but not the Vmax C. always just change the Vmax D. increase the Km but not change the Vmax
  • 79. • The most likely effect of a non-competitive inhibitor on an Michaelis-Menten enzyme is to A. Increase the Vmax B. Decrease the Vmax C. Increase both the Vmax and the Km D. Decrease both the Vmax and the Km
  • 80. • Competitive inhibitor: Vmax stays the same, but Km increases • Non-competitive inhibitor decreases the turnover number of the enzyme rather than preventing substrate binding- Vmax decreases but Km stays the same. This cannot be overcome with an increase in substrate concentration.
  • 81. Sample questions Which of the following binds to an enzyme at its active site? • A) irreversible inhibitor • B) reversible competitive inhibitor • C) reversible noncompetitive inhibitor • D) more than one correct response • E) no correct response An uncompetitive inhibitor binds to _____. • (a) E • (b) ES • (c) P • (d) a and b • (e) a and c
  • 82.
  • 83.
  • 84.
  • 85. Sample questions A reversible inhibitor that can bind to either E alone or the ES complex is referred to as a _____. • (a) competitive inhibitor. • (b) non-competitive inhibitor. • (c) uncompetitive inhibitor. • (d) suicide inhibitor. • (e) irreversible inhibitor.
  • 86. Sample questions A competitive inhibitor of an enzyme is usually • A.a highly reactive compound • B.a metal ion such as Hg2+ or Pb2+ • C.structurally similar to the substrate. • D.water insoluble The enzyme inhibition can occur by • A.reversible inhibitors • B.irreversible inhibitors • C.Both (a) and (b) • D.None of these
  • 87. Sample questions In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect? • A.It moves the entire curve to right • B.It moves the entire curve to left • C.It changes the x-intercept • D.It has no effect on the slope
  • 88. Sample questions Non-competitive inhibitor of an enzyme catalyzed reaction • A.decreases Vmax • B.binds to ES • C.both (a) and (b) • D.can actually increase reaction velocity in rare cases
  • 89. Sample questions A classical uncompetitive inhibitor is a compound that binds • A.reversibly to the enzyme substrate complex yielding an inactive ESI complex • B.irreversibly to the enzyme substrate complex yielding an inactive ESI complex • C.reversibly to the enzyme substrate complex yielding an active ESI complex • D.irreversibly to the enzyme substrate complex yielding an active ESI complex
  • 91. Sample questions • Two curves showing the rate versus substrate concentration are shown below for an enzyme catalyzed reaction. One ‐ curve is for the reaction in the presence of substance X. The other curve is for data in the absence of substance X. Examine the curves and tell which statement below is true. • A) The catalysis shows Michaelis‐Menten kinetics with or without X. • B) X increases the activation energy for the catalytic reaction. • C) X could be a competitive inhibitor. • D) X is an activator of the enzyme.
  • 92. Sample questions Allosteric enzymes are • A.similar to simple enzyme • B.smaller than simple enzyme • C.larger and more complex than simple enzyme • D.smaller than simple enzyme but not complex Which statement is false about allosteric regulation? • A. It is usually the mode of regulation for the last step in reaction pathways since this step produces the final product. • B. Cellular response is faster with allosteric control than by controlling enzyme concentration in the cell. • C. The regulation usually is important to the conservation of energy and materials in cells. • D. Allosteric modulators bind non-covalently at sites other than the active site and induce conformational changes in the enzyme.
  • 93. Sample questions Allosteric modulators seldom resemble the substrate or product of the enzyme. What does this observation show? • A) Modulators likely bind at a site other than the active site. • B) Modulators always act as activators. • C) Modulators bind non-covalently to the enzyme. • D) The enzyme catalyzes more than one reaction.
  • 94. Sample questions • Some enzymatic regulation is allosteric. In such cases, which of the following would usually be found? • A) cooperativity • B) feedback inhibition • C) both activating and inhibitoryactivity • D) an enzyme with more than one subunit • E) the need for cofactors
  • 95. Sample questions • Describe allosteric regulation of enzyme activity? An allosteric enzyme is one in which the activity of the enzyme can be controlled by the binding of a molecule to the “allosteric site”, somewhere other than the active site. Thus allosteric control of an enzyme can be classed in two ways. A positive allosteric regulation is the binding of a molecule to the enzyme which increase the rate of reaction. The opposite is a negative allosteric regulation. An example for this is phosphofructokinase, which is promoted by a high AMP concentration, and inhibited by a high ATP concentration.
  • 96. • This small protein can have dramatic effects on the activities of enzymes in response to changes in intracellular calcium ion concentration: A. Calcitonin B. Calsequestrin C. Calmodulin D. Calcitriol
  • 97. Non-covalent Interactions Protein-Protein Interactions • Calmodulin (CALcium MODULted proteIN) – Binding of Ca++ to calmodulin changes its shape and allows binding and activation of certain enzymes
  • 98. Sample questions • Which statement is false about covalent modification? • A) It is reversible. • B) It is slower than allosteric regulation. • C) It is irreversible. • D) Phosphorylation is a common covalent modification.
  • 99. Sample questions Protein kinases are enzymes that act on other enzymes by adding phosphates groups. When the enzyme is phosphorylated, it changes its activity (it becomes more or less active, depending on the enzyme). This regulatory mechanism of enzymatic activity is called: • A) Allosteric Control • B) Competitive inhibition • C) Covalent Modification • D) Isozymes Modification • E) Zymogen activation
  • 101. Sample questions • Glycolytic pathway regulation involves • A. allosteric stimulation by ADP • B. allosteric inhibition by ATP • C. feedback, or product, inhibition by ATP • D. all of the above • Why does the glycolytic pathway continue in the direction of glucose catabolism? • A. There are essentially three irreversible reactions that act as the driving force for the pathway • B. High levels of ATP keep the pathway going in a forward direction • C. The enzymes of glycolysis only function in one direction • D. Glycolysis occurs in either direction
  • 102. Sample questions The released energy obtained by oxidation of glucose is stored as A. a concentration gradient across a membrane B. ADP C. ATP D. NAD+ A kinase is an enzyme that A. removes phosphate groups of substrates B. uses ATP to add a phosphate group to the substrate C. uses NADH to change the oxidation state of the substrate D. removes water from a double bond
  • 103. Sample questions • For every one molecule of sugar glucose which is oxidized __________ molecule of pyruvic acid are produced. • A.1 • B.2 • C.3 • D.4 • The enzymes of glycolysis in a eukaryotic cell are located in the • A.intermembrane space • B.plasma membrane • C.cytosol • D.mitochondrial matrix
  • 104. Sample questions • Which of the following is not true of glycolysis? • A.ADP is phosphorylated to ATP via substrate level phosphorylation • B.The pathway does not require oxygen • C.The pathway oxidizes two moles of NADH to NAD+ for each mole of glucose that enters • D.The pathway requires two moles of ATP to get started catabolizing each mole of glucose • ATP is from which general category of molecules? • A.Polysaccharides • B.Proteins • C.Nucleotides • D.Amino acids
  • 105. Sample questions • Which of the following regulates glycolysis steps? • A.Phosphofructokinase • B.Hexose kinase • C.Pyruvate kinase • D.All of these
  • 106. Sample questions • Which of the following is not a mechanism for altering the flux of metabolites through the rate-determining step of a pathway? • A. Allosteric control of the enzyme activity • B. Block active sites • C. Genetic control of the enzyme concentration • D. Covalent modification of the enzyme • Phosphofructokinase, the major flux-controlling enzyme of glycolysis is allosterically inhibited and activated respectively by • A.ATP and PEP • B.AMP and Pi • C.ATP and ADP • D.Citrate and ATP
  • 107. • Where does glycolysis occur? A. inner membrane of mitochondria B. matrix of mitochondria C. stroma of chloroplast D. cytoplasm
  • 108. • Sports physiologists wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds? A. oxygen B. ATP C. lactate D. carbon dioxide
  • 110. Sample questions • There are four enzymes of gluconeogenesis that circumvent the irreversible steps in glycolysis. When starting with the substrate pyruvate or lactate they are • A. Hexokinase, phosphofructokinase-1, phosphofructokinase-2 and pyruvate kinase • B. Pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase • C. Glycerol kinase, glycerol-3-phosphate dehydrogenase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase • D. Amino transferase, phosphoenolpyruvate carboxykinase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase
  • 111. Sample questions • The enzymes that remove phosphate groups during the process of gluconeogenesis and circumvent two of the three irreversible reactions of glycolysis are • A. Pyruvate kinase and glycerol kinase • B. Phosphoenolpyruvate carboxykinase and glycerol kinase • C. 3-Phosphoglycerate kinase and fructose-1,6- bisphosphatase • D. Fructose-1,6-bisphosphatase and glucose-6- phosphatase
  • 112. Glycolysis <-> gluconeogenesis Gluconeogenesis is not the reversal of glycolysis !!! Glycolysis: in the cytosol Gluconeogenesis: major part in cytosol -> 1st step in mitochondria -> shuttle Biotin: prosthetic group -> carrier for CO2 Reverse reaction of glycolysis thermodynamically not favorable !!! 112
  • 113. Sample questions • The most important control step in gluconeogenesis is fructose-1,6- bisphosphatase. All of the following statements are true EXCEPT • A. Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate to fructose-6-phosphate • B. During times when insulin is high, fructose-1,6-bisphosphatase is inhibited by fructose-2,6-bisphosphate • C. During a fast or exercise when glucagon and/or epinephrine are high, fructose-1,6-bisphosphatase is active because of the absence of fructose-2,6-bisphosphate • D. Glycolysis or gluconeogenesis cannot be active at the same time. If they were is would be a futile cycle
  • 114. Sample questions • In the liver, glucagon will activate • A. Glycolysis and glycogen synthesis • B. Gluconeogenesis and glycogenolysis • C. Gluconeogenesis and glycogen synthase • D. Gluconeogenesis and glycogen synthesis • Which of the following statements about hormonal levels during different states is true? • A. During the time you are eating a high carbohydrate mixed meal, the insulin to glucagon ratio will decrease • B. When passing from the fed to fasting state, insulin and glucagon usually decrease • C. When playing basketball, epinephrine is usually low and insulin is high • D. After running for 20 miles, epinephrine and glucagon are high and insulin is low
  • 115. Sample questions • All of the following will result in activation of glycogen phosphorylase in skeletal muscle EXCEPT • A. Increased concentrations of AMP from contraction of muscle • B. Increased epinephrine and cAMP • C. Increased cytosolic [Ca++] • D. Increased protein phosphatase • E. Increased activity of glycogen phosphorylase kinase
  • 116. • All of the following statements concerning glycogen synthesis and glycogenolysis are true EXCEPT A. High blood glucose and high insulin will activate glycogen synthesis and inhibit glycogen phosphorylase B. A low insulin to glucagon ratio will activate glycogen phosphorylase and inhibit glycogen synthase C. Being hit in the head with a bat will activate glycogen synthesis and inhibit glycogen phosphorylase D. Taking this test will activate glycogen phosphorylase and inhibit glycogen synthase
  • 118. Sample question • Atherosclerosis can cause blood • A. thinning • B. blockage • C. thickening • D. none of these
  • 119. Sample question • Ketosis is ascribed in part to: – A. Slowdown in fat metabolism – B. An insufficient intermediates of TCA cycle – C. An underproduction of acetyl-CoA – D. An inhibition of glycogen synthesis
  • 120. Sample question • In the intestine, the dietary fats are hydrolyzed by • A.triacylglycerol lipase • B.adenylate cyclase • C.pancreatic lipase • D.protein kinase
  • 121. Sample question • In eukaryotes fatty acid breakdown occurs in • A. mitochondrial matrix • B. cytosol • C. cell membrane • D. endoplasmic reticulum
  • 122. Sample question • Fatty acid synthesis takes place in • A. mitochondria • B. cell membrane • C. cytosol • D. endoplasmic reticulum
  • 123. Sample question • Chylomicrons are synthesized in • A. blood • B. liver • C. intestine • D. pancreas
  • 124. Sample question • VLDLs are synthesized in • A. blood • B. liver • C. intestine • D. pancreas
  • 125. Sample question • Cholestrol is the precursor of • A. steroid hormones • B. vitamin A • C. bile salts • D. both (a) and (c)
  • 127. Sample Questions • A biological redox reaction always involves • A.an oxidizing agent • B.a gain of electrons • C.a reducing agent • D.all of these • Coenzyme Q is involved in electron transport as • A.directly to O2 • B.a water-soluble electron donor • C.covalently attached cytochrome cofactor • D.a lipid-soluble electron carrier
  • 128. Sample Questions • FAD is reduced to FADH2 during • A. electron transport phosphorylation • B. lactate fermentation • C. Krebs cycle • D. glycolysis • During glycolysis, electrons removed from glucose are passed to • A. FAD • B. NAD+ • C. acetyl CoA • D. pyruvic acid
  • 129. Sample Questions • Almost all of the oxygen (O2) one consumes in breathing is converted to: • A.acetyl-CoA. • B.carbon dioxide (CO2). • C.carbon monoxide and then to carbon dioxide. • D.water. • The carbon dioxide is primary a product of • A.Krebs cycle • B.glycolysis • C.electron transport phosphorylation. • D.lactate fermentation.
  • 130. Sample Question • Which of the following statements about the chemiosmotic theory is correct? • A. Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane. • B. It predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrane. • C. The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes. • D. The membrane ATP synthase has no significant role in the chemiosmotic theory.
  • 131. Sample Question • Uncoupling of mitochondrial oxidative phosphorylation: • A. allows continued mitochondrial ATP formation, but halts O2 consumption. • B. halts all mitochondrial metabolism. • C. halts mitochondrial ATP formation, but allows continued O2 consumption. • D. slows the conversion of glucose to pyruvate by glycolysis.
  • 132. Sample Questions • Where does Oxidative Phosphorylation occur? the inner membrane of the cell mitochondria • In the reaction in which FADH2 transfers hydrogen atoms to Q, which molecule is oxidized and which is reduced?
  • 133. • Cellular respiration takes place mostly in: A. chloroplasts B. ribosomes C. nucleus D. mitochondria
  • 134. • Which of the following is not present during the TCA cycle? A. NADH B. O2 C. CO2 D. ATP
  • 135. • Which of the following is a list of the stages in the correct order? A. pyruvate oxidation, glyocolysis, the citric acid cycle, and oxidative phosphorylation B. oxidative phosphorylation, glyocolysis, the citric acid cycle, and pyruvate oxidation C. glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation D. glycolysis, the citric acid cycle, pyruvate oxidation, and oxidative phosphorylation
  • 136. • What are the products of the citric acid cycle? A. NADH, ATP, FADH2, and CO2 B. O2, ADP, 1 FAD, and NAD+ C. Glucose, ATP, O2, and NADH D. heat, H2O, NADH, and pyruvate
  • 137. • Which of the following is NOT a way of producing ATP in humans? A. Krebs Cycle B. Alcohol Fermentation C. Lactic Acid Fermentation D. Glycolysis
  • 138. • Which of the following is an aerobic product of pyruvate catabolic metabolism? • A lactate • B ethanol. • C acetyl CoA • D glucose.
  • 139. • Someone had hypoglycemic coma after he injected himself with a large dose of insulin. All of the following contributed to his coma EXCEPT A. Insulin inhibited gluconeogenesis in the liver B. Insulin activated glycogen phosphoryalse in the liver C. Insulin increased Glut4 in the muscle membrane D. Insulin inhibited the mobilization of free fatty acid from adipose and the entrance into liver mitochondria
  • 140. • The insulin to glucagon ratio is low as it usually is in both Type I and Type II diabetics. During and immediately after a high carbohydrate meal, you would expect A. The storage of glucose in muscle to be less than normal for type 2 patients but normal for type 1 patients B. The storage of glucose in muscle to be less than normal for type 1 patients but normal for type 2 patients C. The storage of glucose in muscle and liver to be less than normal D. The storage of glucose in muscle and liver to be greater than normal
  • 141. • All other things being constant, an increase in glucagon would result in an increase in A. Fatty acid synthesis in adipose tissue B. β-oxidation in liver C. Protein synthesis in muscle D. Glycogenolysis in muscle
  • 142. • The pathway for the synthesis of glycogen from portal blood glucose in the liver: A. Is inhibited by glucose B. Is inhibited by insulin C. Uses activated glycogen phosphorylase D. Is inhibited by high cAMP
  • 143. • Epinephrine: • A stimulates the synthesis of glycogen in liver cells. • B has no effect on cAMP in muscle cells • C has a direct effect on the glucose transporter in muscle cells. • D stimulates the degradation of glycogen in muscle cells.
  • 144. • The TCA cycle: A. Is found in the cytosol B. Is controlled by the ADP/ATP ratio and the NADH concentration C. Is also called the Cori cycle D. Produces most of the water made in humans
  • 145. • The Krebs Cycle begins when pytuvic acid produced by glycolsis enters the A. cytosol B. air C. mitochondrion D. nuclear
  • 146. • During the fasting state, the release of fatty acids from adipose tissue is increased. At least part of the signal for this release is carried by A. insulin from beta-cells of the pancreas B. epinephrine from alpha-cells of the pancreas C. epinephrine from the adrenal medulla D. glucagon from the adrenal medulla
  • 147. • In aerobic organisms growing in the presence of oxygen, the NADH produced by glycolysis ultimately donates its high-energy electrons to . A. electron transport chains in the mitochondria B. ATP C. pyruvate D. glucose
  • 148. • Cellular respiration takes place mostly in: A. chloroplasts B. ribosomes C. nucleus D. mitochondria
  • 149. • The main purpose of the electron transport chain is to: A. Use high energy electrons from other cycles to convert ADP into ATP B. Maintain a stable balance of high energy electrons C. Constantly distribute electrons throughout the cell D. Tell the cell when glycolysis should stop or start
  • 150. • Oxidative phosphorylation: A. Is anaerobic B. Requires AMP C. Requires the electron transport system D. Is not dependent upon development of a proton gradient
  • 151. • Where are the proteins of the electron transport chain located? A. cytosol B. mitochondrial outer membrane C. mitochondrial inner membrane D. mitochondrial matrix
  • 152. • The ATP synthase responsible for most of the ATP synthesis in the body is located: A. On the outer side of the outer mitochondria membrane B. On the inner side of the outer mitochondria membrane C. On the outer side of the inner mitochondria membrane D. On the inner side of the inner mitochondria membrane
  • 153. • In the electron transport chain, the final electron acceptor is A. oxygen B. a molecule of carbon dioxide C. a molecule of water D. ADP
  • 154. • A mitochondrion is producing ATP at a constant rate and, then, a chemical uncoupler is added. Compared to before the uncoupler was added: A. Less heat would be produced B. Less water would be produced C. More NADH would be oxidized D. The proton gradient across the membrane would be increased
  • 155. Matrix H+ + NADH NAD+ + 2H+ 2H+ + ½ O2 H2O 2 e- I Q III IV cyt c uncoupler 4H+ 4H+ 2H+ H+ Intermembrane Space With uncoupler present, there is no DpH or DY.  DG for H+ ejection is zero  DG for e- transfer coupled to H+ ejection is maximal (spontaneous). Respiration proceeds in the presence of an uncoupler, whether or not ADP is present.
  • 156. • A direct inhibitor of the ATP synthase (i.e. the ability to make ATP) in the presence of active electron transport: • A. would increase the membrane potential. • B would decrease the membrane potential. • C would increase electron transport rates • D would decrease the pH gradient.
  • 157. • During chemiosmosis, A. energy is released as H+ ions move across mitochondrial membranes B. H+ do NOT play any role in the production of ATP molecules C. a concentration gradient is generated when large numbers of H+ ions are passively transported from the matrix of the mitochondrion to the mitochondrion's intermembrane space D. ATP is synthesized when H+ ions move through a channel in ATP synthase
  • 158. • The chemiosmotic theory holds all of the following EXCEPT: A. The cytosol has a higher pH than the matrix B. In the absence of a proton motive force, ATP will not be synthesized C. The electrochemical potential comes from both the electrical potential and the proton concentration gradient D. Electrons are passed from one carrier to the next as protons are pumped across the inner mitochondrial membrane
  • 159. • During REDOX reactions in cellular respiration, glucose undergoes _____ while oxygen undergoes______ A. reduction ..... oxidation B. oxidation ..... reduction C. no change ..... oxidation D. none of the above
  • 160. • Anemia, hemorrhage, and chronic obstructive pulmonary disease can all cause metabolic acidosis. The best explanation is that the lack of oxygen causes A. a decrease in insulin that, in turn, increases anaerobic glycolysis in the brain B. a decrease in oxidative phosphorylation so the cells have to rely upon anaerobic glycolysis C. a decrease in the removal of CO2 from the blood. The resulting decrease in pH causes an increase in glycolysis in most cells D. an increase in glycolysis in red blood cells
  • 161. • Hydrolysis of a triglyceride produces A. many amino acids B. different types of nucleotides C. fatty acids and glycerol D. monosaccharides
  • 162. • Free fatty acids are able to travel from adipose tissue to muscle or liver A. As independent water soluble compounds in the blood B. By using receptors on red blood cells C. Bound to serum proteins D. By using enzymes that modify them
  • 163. • When the concentration of epinephrine or glucagon is high, they bind to receptors on adipose cell membrane and all of the following can be expected to occur EXCEPT A. Triacylglycerol is hydrolyzed to free fatty acids and glycerol B. Free fatty acids are carried to most tissues of the body by albumin C. Fatty acids are activated, enter the mitochondria, and are oxidized by β-oxidation and the TCA cycle D. Increased β-oxidation increases glycolysis in resting muscle
  • 165. Sample question • The site of amino acid catabolism is the: A. Stomach B. Small intestine C. Large intestine D. Liver
  • 166. Sample question • The first step in the catabolism of most amino acids is • A. Removal of carboxylate groups • B. Enzymatic hydrolysis of peptide bonds • C. Removal of the amino group • D. Zymogen cleavage
  • 167. Sample question Which of the following is true of urea? • A. more toxic to human cells than ammonia • B. the primary nitrogenous waste products of humans. • C. insoluble in water • D. the primary nitrogenous waste product of most aquatic invertebrates
  • 168. Sample question A glucogenic amino acid is one which is degraded to • A. keto-sugars • B. either acetyl CoA or acetoacetyl CoA • C. pyruvate or citric acid cycle intermediates • D. none of the above
  • 169. Sample question Transamination is the process where • A. carboxyl group is transferred from amino acid • B. α-amino group is removed from the amino acid • C. polymerization of amino acid takes place • D. none of the above
  • 170. Sample question Transamination is the transfer of an amino • A. acid to a carboxylic acid plus ammonia • B. group from an amino acid to a keto acid • C. acid to a keto acid plus ammonia • D. group from an amino acid to a carboxylic acid
  • 172. Sample Question • In inherited deficiency of hypoxanthine guanine phosphoribosyl transferase (A) De novo synthesis of purine nucleotides is decreased (B) Salvage of purines is decreased (C) Salvage of purines is increased (D) Synthesis of uric acid is decreased
  • 173. Sample Question • Which of the following is a required substrate for purine biosynthesis ? (A) 5- methyl thymidine (B) Ribose phosphate (C) PRPP (D) 5-Fluoro uracil
  • 174. Sample Question • The conversion of Inosine mono phosphate (A) To Adenosine mono phosphate (AMP) is inhibited by Guanosine mono phosphate (GMP) (B) To AMP requires uridine mono phosphate (UMP) (C) To GMP requires GMP kinase (D) To GMP requires Glutamine
  • 175. HN N O N N Ribose-P Aspartate + GTP N N NH N N Ribose-P COO- -OOC HN N O N N Ribose-P O H Adenylosuccinate xanthine monophosphate XMP IMP IMP dehydrogenase NAD+ NADH A.S. synthetase GDP N N NH2 N N Ribose-P HN N O N N H2N Ribose-P A.S. lyase fumarate glutamine + ATP Glutamate + AMP + PPi AMP GMP Synthesis of adenine and guanine nucleotides IMP to AMP and GMP • Glutamine, NAD, ATP used in GMP production • Aspartate, GTP used AMP production
  • 177. Sample questions • Both strands of DNA serve as templates concurrently in • A. replication • B. excision repair • C. mismatch repair • D. none of these
  • 178. • Proofreading activity to maintain the fidelity of DNA synthesis • A. occurs after the synthesis has been completed • B. is a function of the 3'-5' exonuclease activity of the DNA polymerases • C. requires the presence of an enzyme separate from the DNA polymerases • D. occurs in prokaryotes but not eukaryotes
  • 179. • Which of the following repairs nicked DNA by forming a phosphodiester bond between adjacent nucleotides? • A. Helicase • B. DNA gyrase • C. Topoisomerases • D. DNA ligase
  • 180. • The replication of chromosomes by eukaryotes occurs in a relatively short period of time because • A. the eukaryotes have more amount of DNA for replication • B. the eukaryotic replication machinery is 1000 times faster than the prokaryotes • C. each chromosome contains multiple replicons • D. eukaryotic DNA is always single stranded
  • 181. • During which of the following process a new copy of a DNA molecule is precisely synthesized? • A. Trasformation • B. Transcription • C. Translation • D. Replication
  • 182. • Which of the following enzyme adds complementary bases during replication? • A. Helicase • B. Synthesase • C. Replicase • D. Polymerase
  • 183. • Which of the following enzymes unwind short stretches of DNA helix immediately ahead of a replication fork? • A. DNA polymerases • B. Helicases • C. Single-stranded binding proteins • D. Topoisomerases
  • 184. • Which DNA polymerase removes RNA primers in DNA synthesis? • A. Polymerase I • B. Polymerase II • C. Polymerase III • D. none of these
  • 185. DNA polymerases are specialized for different roles in the cell
  • 186. • Enzyme, responsible for proofreading base pairing is • A. DNA polymerase • B. Telomerase • C. Primase • D. DNA ligase
  • 187. • DNA helicase is used to • A. unwind the double helix • B. interact the double helix closely • C. break a phosphodiester bond in DNA strand • D. none of the above
  • 188. • The synthesis of DNA by DNA polymerase occurs in the • A. 3' to 5' direction • B. 5' to 5' direction • C. 5' to 3' direction • D. 3' to 3' direction
  • 189. • The 5' and 3' numbers are related to the • A. length of the DNA strand • B. carbon number in sugar • C. the number of phosphates • D. the base pair rule
  • 190. • What is the main damaging effect of UV radiation on DNA? • A. Depurination • B. Formation of thymine dimers • C. Single strand break • D. Dehydration
  • 191. What is the function of DNA polymerase? Explain how a DNA molecule contains the information necessary to produce copies of itself. • DNA polymerase is an enzyme that catalyzes the reaction that adds nucleotides to a growing DNA strand while replication occurs. This enzyme also has a role in repairing errors in DNA molecules. • Each strand of a DNA molecule serves as a template for the synthesis of a complementary DNA strand using base pair relationships. This makes it possible to produce an exact copy of a DNA molecule.
  • 193. Sample questions • Which of the following enzyme is used for synthesis of RNA under the direction of DNA? • A. RNA polymerase • B. DNA ligase • C. DNA polymerase • D. RNA ligase
  • 194. • Which of the following is a product of transcription? • A. mRNA • B. tRNA • C. rRNA • D. all of these
  • 195. • Recognition/binding site of RNA polymerase is called • A. receptor • B. promoter • C. facilitator • D. terminator
  • 196. • An mRNA transcript of a gene contains • A. a start codon • B. a stop codon • C. a terminator • D. all of these
  • 197. • The components found in all prokaryotic transcription terminators is • A. a poly-U region • B. Rho factor • C. a hairpin structure • D. none of these
  • 198. • Where in the cell is the DNA transcribed into mRNA? • A.Cytoplasm • B.Nucleus • C.Golgi • D.Cell cytoskeleton
  • 199. • Which of the following does NOT happen during hnRNA processing? • A. Introns are spliced out. • B. A 7-methylguanosine cap is added to the 5' end of the RNA. • C. A poly A tail is added. • D. Ribosomes bind and begin translation.
  • 200. • Since the two strands of the DNA molecule are complementary, for any given gene: • A. The RNA polymerase can bind to either strand. • B. Only one strand actually carries the genetic code for a particular gene. • C. Each gene possesses an exact replica so that no mutation occurs. • D. A gene transcribed in the 5’ to 3’ direction on one strand can be transcribed in the 3’ to 5’ direction on the other strand.
  • 202. Sample questions • The site of protein synthesis is • A. Ribosome • B. Nucleus • C. Endoplasmic reticulum • D. Chromosome
  • 203. Sample questions • The structure in a bacterium that indicates an active site for protein synthesis is • A. a chromosome. • B. a cell membrane, • C. a flagellum. • D. a polysome.
  • 204. Sample questions • Which of the following is not necessary for protein synthesis to occur, once transcription is completed? • A. tRNA • B. Ribosomes • C. mRNA • D. DNA
  • 205. Sample questions • During the process of translation: • A. the peptide is ‘passed’ from the tRNA in the P-site to the tRNA in the A-site. • B. incoming tRNAs must first bind to the E-site. • C. initiation begins with the binding of the ribosomal SSU to the poly-A tail of the mRNA. • D. the mRNA is translated by one ribosome at a time.
  • 206. • The nucleolus of the nucleus is the site where: • A. RNA processing occurs • B. rRNA is transcribed and ribosomal subunits are assembled • C. tRNA are charged with amino acids • D. mRNA is translated into protein
  • 207. Ribosome Assembly: takes place largely in a specialized domain of the nucleus, the nucleolus
  • 208. • The ribosomes are composed of • A. proteins • B. RNA • C. both (a) and (b) • D. lipids
  • 209. • Which is required for protein synthesis? • A. tRNA • B. mRNA • C. rRNA • D. All of these
  • 210. • In the genetic code there are: • A. more tRNAs than codons. • B. more codons than amino acids. • C. more nucleotides than codons. • D. the same number of codons and amino acids
  • 211. • he anticodon of tRNA • A. binds to rRNA • B. binds to an amino acid • C. binds to the Shine Dalgarno sequence • D. binds to an mRNA codon
  • 212. • Initiation of eukaryotic translation begins when the: • A. large and small subunits link together, then bind to the mRNA. • B. ribosomal small subunit holding an initiator tRNA binds to the 5’ end of mRNA. • C. ribosome binds to of the start codon and an initiator tRNA enters the ribosome. • D. initiator tRNA binds to the start codon, followed by binding of the ribosome large subunit.
  • 213. • On the ribosome, mRNA binds • A. between the subunits • B. to the large subunit • C. to the small subunit • D. none of these
  • 214. In addition to the APE sites there is an mRNA binding groove that holds onto the message being translated
  • 215. • The peptidyl transferase reaction occurs • A. on the large subunit • B. on the small subunit • C. between the subunit • D. none of these
  • 216. • Ribosomes select the correct tRNAs • A. based on the aminoacyl group • B. solely on the basis of their anticodons • C. depending on their abundance in the cytosol • D. with the least abundant anticodons
  • 217. • Which of the following amino acid starts all proteins synthesis? • A. Glycine • B. Proline • C. Thymine • D. Methionine
  • 218. • The growing polypeptide chain is released from the ribosomes when • A. a chain terminating codon is reached • B. a chain terminating tRNA binds to the ribosome • C. the 7-methyl guanosine cap is reached • D. the poly A tail is reached
  • 219. What is a gene? • A gene is a region of DNA whose final product is either a polypeptide or an RNA molecule
  • 221. Sample questions • The lac repressor is a • A. carbohydrate. • B. DNA molecule. • C. RNA molecule. • D. protein molecule.
  • 222. • What would be the effect of a mutation in the operator that blocked the lac repressor binding? • A. The genes would be inducible by lactose. • B. The lacZYA genes would be expressed constitutively. • C. The lacZYA genes would not be expressed. • D. The lacZYA genes would be repressed by lactose.
  • 223. • A regulatory site within the leader sequence of the tryptophan operon that controls this operon by diminishing transcription is called: • A.operator • B.upregulator • C.repressor • D.transcriptor
  • 224. • Which level of primary control in eukaryotic gene activity involves processing early RNA transcripts to mRNA and control of the rate at which mRNA leaves the nucleus? • A. transcriptional control • B. translational control • C. posttranscriptional control • D. posttranslational control
  • 225. • An enhancer site is • A. part of an operon. • B. found only in prokaryotes. • C. located at a distance from the gene it affects. • D. an attachment site for RNA polymerase.
  • 226. Cell growth and carcinogenesis
  • 227. Sample questions • The event(s) which does not occur during interphase, is/are • A. Chromatin condenses • B. Protein Synthesis • C. Organelles replication • D. DNA replication
  • 228. The Cell Cycle • 2 major phases – Interphase – Mitosis
  • 229. • At the center of the cell cycle control system is Cdk, a protein that • A. is phosphorylated to become active • B. binds to different cyclins • C. is only active during mitosis • D. manufactures growth factors
  • 230. Sample questions • An oncogene is • A. a viral gene with no relation to the host cell's genes. • B. a mutated form of a proto-oncogene. • C. a bacterial gene that causes cancer in the host. • D. a gene that turns off cellular reproduction.
  • 231. Questions that have been reviewed
  • 232. The complementary sequence in the standard 5’ 3’ notation for GATCAA is _______ • TTGATC
  • 233. List at least 3 non-covalent interactions in the biomolecules • van der Waals • Hydrogen bonds • Ionic bonds • Hydrophobic interactions
  • 234. Explain the hydrophobic interactions • Hydrophobic interactions minimize interactions of non-polar components with aqueous solvent.
  • 235. How are proteins separated by electrophoresis? • The separation of proteins is done by charge. pH is kept higher then the isoelectric pH (pI). So, the proteins will have negative charge and so the proteins will move towards the positive electrode.
  • 236. Explain the definition of domain of proteins. • FFuunnddaammeennttaall ffuunnccttiioonnaall && tthhrreeee ddiimmeennssiioonnaall ssttrruuccttuurraall uunniittss ooff pprrootteeiinnss..
  • 237. What is the function of chaperones in protein folding? List at least one role. • AAssssiisstt ffoollddiinngg • PPrrootteecctt aggregation • SSoommee ttiimmeess kkeeeepp pprrootteeiinn uunnffoollddeedd uunnttiill ssyynntthheessiiss iiss ccoommpplleettee..
  • 238. Explain the difference between reversible denaturation and irreversible denaturation of proteins. • Some proteins can refold upon removal of denaturant. Other can’t refold upon the removal of denaturant.
  • 239. Molecules contain both a positive and a negative charged functional group is called _____ • zwitterion
  • 240. Hemoglobin is an allosteric protein that can exist in two states: R (relaxed) and T (taut). ____ state binds oxygen tighter. • R (relaxed)
  • 241. The change in oxygen affinity with pH is known as the Bohr effect. Hemoglobin oxygen affinity is ____ (increased/decreased) as the acidity increases. • Reduced or decreased
  • 242. Proteins that recognize and bind to a particular antigen with very high specificity belong to a group of serum proteins called ______. • Immunoglobulins or antibodies
  • 243. What is the shape of the oxygen hemoglobin dissociation curve? How does the shape of the curve relate to the cooperative binding of O2? • Sigmoid or sigmoidal curve • The small change of oxygen partial pressure results in a greater change of the hemoglobin binding affinity to oxygen.
  • 244. How does the shape of oxygen–hemoglobin dissociation curve influence loading of oxygen at the lung and unloading of oxygen at the tissue level? • There are a high oxygen partial pressure in the lung and a low oxygen partial pressure in the other tissues. At high oxygen pressure, the hemoglobin tends to be saturated with oxygen while, at low oxygen pressure hemoglobin tends to unload all the oxygen molecules.
  • 245. List at least 3 factors that influence the binding of hemoglobin to oxygen. • carbon dioxide or CO2 • pH or acidity • Oxidative state of Fe in the heme group • 2,3-DPG or 2,3-BPG • Carbon monoxide or CO
  • 246. _____ are long polymers of nucleotides. • Nucleic acids
  • 247. The maximal UV absorbance of nucleic acids and proteins are at the wavelength of ___ nm and ___ nm, respectively. • 260, 280
  • 248. The sugar groups in the nucleic acids are ___ (D/L) ribose while the residues in the protein are ___ (D/L) amino acids. • D, L
  • 249. Polymer of nucleotides linked in a direction from ribose carbon ___ (3’/5’) to carbon ___ (3’/5’) by ______bonds. • 5’, 3’, phosphodiester
  • 250. List at least 3 types of RNA molecules in the biological system. • ribosomal RNA or rRNA • messenger RNA or mRNA • transfer RNA or tRNA • microRNA or miRNA • small RNA or siRNA • long non-coding RNA • short non-coding RNA
  • 251. Besides hydrophobic interactions, hydrogen bonding, and electrostatic interactions, nucleic acids have one more type of noncovalent interaction that is called ____. • Stacking interactions or base stacking (interactions between stacked bases)
  • 252. What is DNA melting temperature? • the temperature at which a DNA double helix dissociates into single strands
  • 253. What is the purpose of using the polymerase chain reaction (PCR) in diagnosis or research? • to rapidly amplify sequences of DNA
  • 254. In the nucleosome, DNA wrapped around an octamer protein complex that are called ____. • histone
  • 255. DNA binding proteins bind DNA in two ways: sequence-specific binding and non-sequence specific binding. Please list two example of non-sequence specific binding proteins. • Single-stranded nucleic acid binding proteins (SSB) • Exonucleases, RNase, or DNase • RNA polymerases or DNA polymerases • Topoisomerases
  • 256. Define the enzyme active site. • The active site of an enzyme represents as the small region at which the substrate (s) binds and participates in the catalysis
  • 257. Feedback Inhibition is a type of allosteric regulation for enzyme. When does feedback inhibition occur? • This occurs when an end-product of a pathway accumulates as the metabolic demand for it declines.
  • 258. For every molecule of glucose that enters glycolysis, there is an initial investment of 2 molecules of ____ before the subsequent generation of ____ . • ATP, ATP
  • 259. What is the purpose of glucagon? • It slows down glycolysis when blood sugar is low and stimulates the formation of more glucose.
  • 260. An enzyme that catalyzes the phosphorylation of a molecule using ATP is called ____ • Kinase
  • 261. Name two molecules that carries electrons from glycolysis and Krebs Cycle to the electron transport system. • NADH and FADH2
  • 262. Phosphofructokinase-1 (PFK-1) is an enzyme in glycolysis. It’s activity is controlled by a complex allosteric regulation. What is the function of AMP in the PFK-1 regulation? • AMP allosterically activates PFK-1
  • 263. There are three irreversible reactions in the glycolysis. What are the corresponding enzymes that catalyze those reactions? • Hexokinase or Glucokinase • Phosphofructokinase 1 or PFK-1 • Pyruvate Kinase
  • 264. Hexokinase is allosterically inhibited by its product Glucose 6 phosphate. The hexokinase in the liver is called glucokinase. However, glucokinase is not subject to product inhibition by glucose-6-phosphate. What the benefit of this characteristics of glucokinase? • Liver will take up & phosphorylate glucose even when liver glucose-6-phosphate concentration is high.
  • 265. During the Cori cycle, _____ is transported to the liver to regenerate glucose which is returned to muscle tissue. • Lactic acid or lactate
  • 266. Insulin is produced when blood glucose is high. How does insulin regulate the transcription of the glycolysis enzyme in liver, glucokinase? • Insulin activates of transcription of Glucokinase in liver.
  • 267. In the liver, the most important coordinating modulator is fructose 2,6- bisphophate (F2,6BP). It is formed from F6P by the enzyme domain, phosphofructokinase-2 (PFK-2), and broken down by the same enzyme, but at a different domain called fructose 2,6-bisphosphatase (FBPase- 2). How does the balance of PFK-2 to FBPase-2 activity controlled by glucagon? • Glucagon causes the enzyme phosphorylation. Phosphorylation of the enzyme results in the inactivation of the phosphofructokinase-2 activity and activation of the fructose-2,6- bisphosphatase activity.
  • 268. The last product of glycolysis is ____ while the first reactant of Krebs cycle is ____. • Pyruvate, Acetyl Co-A
  • 269. Briefly explain the Cori cycle which is a linked metabolic pathways. • The glucose can enter the blood and be carried to muscles. • Lactic acid is produced by anaerobic glycolysis in the muscles • The lactic acid is sent in the blood to the liver which can convert it back to glucose through gluconeogenesis.
  • 270. What is epinephrine’s role in glycogen and glucose metabolism? • Epinephrine markedly stimulates glycogen breakdown and glycolysis.
  • 271. Palmitic acid, CH3(CH2)14COOH, can maximally yield ____ acetyl-CoAs through ____ cycles of beta-oxidation. • Eight, seven
  • 272. Why can acetone be detected on breath of diabetic patients? • Acetone breath in diabetics is caused by an excess production of ketone bodies. • Glucose is abundant in blood, but uptake by cells in muscle, liver, and adipose cells is low. Cells, metabolically starved, turn to gluconeogenesis and fat/protein catabolism • However, due to excess gluconeogenesis, oxaloacetate is low, so acetyl-CoA from fat/protein catabolism does not go to TCA, but rather to ketone body production.
  • 273. High cholesterol diet leads to ____ (promotion/repression) of LDL receptor synthesis. • repression
  • 274. Chylomicrons are vesicles found in the blood and lymphatic fluid where they serve to transport lipid from the intestine to the liver and to adipose tissue. Of what are the chylomicrons composed? List at least 3 components. • Triglycerides • Cholesterols • lipoproteins • phospholipids • Cholesteryl ester
  • 275. What is the effect of epinephrine and glucagon on triglyceride metabolism? • Epinephrine and glucagon trigger the mobilization of stored triglycerides
  • 276. What is oxidative phosphorylation? • Answer1: Oxidative phosphorylation transfers energy from NADH to ATP. (via chemiosmosis) • Answer2: Oxidative phosphorylation is the process of converting this high redox potential into energy-rich ATP molecules.
  • 277. Oxidative phosphorylation is accomplished via two separate systems in the mitochondrion. What are those two systems? • Electron transport chain system and ATP synthesis system.
  • 278. ATP synthesis is driven by proton motive force. What are the two types of gradient associated with proton motive force? • a proton gradient or pH gradient • a electrical gradient or ion gradient
  • 279. Metabolism of amino acids differs, but all of them require the removal of amino groups. What are the two types of reactions to remove amino groups? • Transamination • Deamination
  • 280. Disposal of ammonia from amino acid metabolism as _____ in most tissues especially in the brain and kidneys, as _____ in the liver, and as _____ in the skeletal muscles. • Glutamine, urea, alanine
  • 281. Based on the catabolic fates of carbon skeleton of amino acids, the amino acids can be classified as ____ or _____. • Glucogenic, ketogenic
  • 282. Dietary nucleotides _____ (do/do not) contribute energy as an energy source material and _____ (are/are not) incorporated into RNA or DNA. • Do not, are not
  • 283. The purine nucleotides are synthesized via two pathways in the body. One is ____ synthesis pathway while the other is ____ pathway. • De novo, salvage
  • 284. The purine synthesis is _____ by PRPP, _____ by IMP, _____ by AMP, and _____by GMP. Fill the blank with activated or inhibited. • Activated, Inhibited, Inhibited, Inhibited,
  • 285. What are the carbohydrate and fat metabolic events occurred in liver during fasting? • The liver first starts glycogen degradation, then gluconeogenesis to maintain blood glucose levels. • The fatty acid oxidation and ketone body production are increased.
  • 286. Insulin promotes the translocation of ______ to the plasma membrane. • GLUT or glucose transporter
  • 287. Why do we say that DNA replication is semiconservative? • The new strands composed of one original strand and one daughter strand
  • 288. DNA polymerases cannot initiate synthesis of a polynucleotide; they can only add nucleotides to the 3’ end. Therefore, a short _____ is required to initiate nucleotide synthesis. • RNA primer
  • 289. Eukaryotic chromosomal DNA molecules have special nucleotide sequences at their ends called ______. • telomeres
  • 290. Why is DNA replication semi-discontinuous? • DNA strands are antiparallel. And, replication process obeys the principle that DNA is synthesized from the 5´ end to the 3´end. • Leading strand synthesized continuously while lagging strand synthesized discontinuously
  • 291. List at least 3 differences between replication and transcription. replication transcription template double strands single strand substrate dNTP NTP primer yes no Enzyme DNA polymerase RNA polymerase product dsDNA ssRNA base pair A-T, G-C A-U, T-A, G-C The whole genome of DNA needs to be replicated, but only small portion of genome is transcribed
  • 292. During transcription, one of the DNA strands called ______ strand is the strand from which the RNA is actually transcribed. The other strand called _____ strand is the strand whose base sequence specifies the amino acid sequence of the encoded protein. • Template, coding
  • 293. What is asymmetric transcription? • Only the template strand is used for the transcription, but the coding strand is not. • The transcription direction on different strands is opposite. 5' 3' 3' 5'
  • 294. The mRNA start codon is ___ in most cases. • AUG
  • 295. Deoxyribonucleotides are formed from their corresponding _____. • ribonucleotides
  • 296. Explain mRNA splicing • During splicing, introns are removed from the strand, and the exons that remain are assembled into a finished strand of mRNA that is ready for translation.
  • 297. What is the consequence of frameshift mutation? • Frameshift mutations result in all subsequent reading frames (codons) being shifted by one or two nucleotides. These shifted frames will code for different amino acids than before, and will result in the creation of a malfunctioning protein.
  • 298. The GUU  GUA transition still codes for Val and it therefore called to be ______ mutation. • nonsense
  • 299. The insertion or deletion of a nucleotide into a gene results in a _____ mutation. • frameshift
  • 300. An incoming aminoacyl-tRNA enters the ribosome at the ___ site. • A
  • 301. ____ are synthesized as inactive precursors that require proteolysis for activation. • zymogen or proenzyme
  • 302. In the operon system, tryptophan acts as a ____ by binding the trp repressor. • Co-repressor