KEY CONCEPTS
8.1 An organism’s metabolism transforms matter and
energy, subject to the laws of thermodynamics
8.2 The free-energy change of a reaction tells us whether or not the reaction occurs
spontaneously
8.3 ATP powers cellular work by coupling exergonic reactions to endergonic reactions
8.4 Enzymes speed up metabolic reactions by lowering energy barriers
8.5 Regulation of enzyme activity helps control metabolism
biological molecules .
CARBOHYDRATES, FATS AND PROTEINS.
includes how large molecules are made from smaller ones, their functions, etc.
made in a very interactive way so that students can understand and clear all their concepts
biological molecules .
CARBOHYDRATES, FATS AND PROTEINS.
includes how large molecules are made from smaller ones, their functions, etc.
made in a very interactive way so that students can understand and clear all their concepts
Electron Transport Chain and oxidative phosphorylationusmanzafar66
substrate level phosphorylation and chemiosmosis
in Eukaryotes and in prokaryotes
in plant and animal
uncoupler oxidative phosphorylation
fat and protein ATP calculation
Biological oxidation and Electron Transport Chain is the most important and confusing topic in biochemistry metabolism, but here we tried to put it in the simplest way easy to learn. This presentation was guided by Dr. Arpita Patel and made by Miss Nidhi Argade.
Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids (anabolism), and the breakdown of proteins by catabolism. ... In humans, non-essential amino acids are synthesized from intermediates in major metabolic pathways such as the Citric Acid Cycle.
Electron Transport Chain and oxidative phosphorylationusmanzafar66
substrate level phosphorylation and chemiosmosis
in Eukaryotes and in prokaryotes
in plant and animal
uncoupler oxidative phosphorylation
fat and protein ATP calculation
Biological oxidation and Electron Transport Chain is the most important and confusing topic in biochemistry metabolism, but here we tried to put it in the simplest way easy to learn. This presentation was guided by Dr. Arpita Patel and made by Miss Nidhi Argade.
Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids (anabolism), and the breakdown of proteins by catabolism. ... In humans, non-essential amino acids are synthesized from intermediates in major metabolic pathways such as the Citric Acid Cycle.
Reference Harper Illustrated book of Biochemistry
Applying laws of Thermodynamics to Biochemistry.
Diferent types of Reactions, exergonic and edergonic,
Illustrated explain of Role of ATP in our body,
Brief concept on ATP production and high energy phosphate,
ATP/ADP cycle and about Creatine Kinase
KEY CONCEPTS
43.1 In innate immunity, recognition and response rely on traits
common to groups of pathogens
43.2 In adaptive immunity, receptors provide pathogen-specific
recognition
43.3 Adaptive immunity defends against infection of body fluids and body cells
43.4 Disruptions in immune system function can elicit or exacerbate disease
KEY CONCEPTS
18.1 Bacteria often respond to environmental change by
regulating transcription
18.2 Eukaryotic gene expression is regulated at many stages
18.3 Noncoding RNAs play multiple roles in controlling gene
expression
18.4 A program of differential gene expression leads to the different cell types in a multicellular organism
18.5 Cancer results from genetic changes that affect cell cycle control
Chapter 16: Molecular Basis of InheritanceAngel Vega
KEY CONCEPTS
16.1 DNA is the genetic material
16.2 Many proteins work together in
DNA replication and repair
16.3 A chromosome consists of a DNA molecule packed together with proteins
Chapter 15: Chromosomal Basis of InheritanceAngel Vega
KEY CONCEPTS
15.1 Morgan showed that Mendelian inheritance has its physical
basis in the behavior of chromosomes: Scientific inquiry
15.2 Sex-linked genes exhibit unique patterns of inheritance
15.3 Linked genes tend to be inherited together because they are located near each other on the same chromosome
15.4 Alterations of chromosome number or structure cause
some genetic disorders
15.5 Some inheritance patterns are exceptions to standard
Mendelian inheritance
KEY CONCEPTS
14.1 Mendel used the scientific approach to identify two laws of inheritance
14.2 Probability laws govern Mendelian inheritance
14.3 Inheritance patterns are often more complex than predicted by simple Mendelian genetics
14.4 Many human traits follow Mendelian patterns of
inheritance
KEY CONCEPTS
13.1 Offspring acquire genes from parents by inheriting
chromosomes
13.2 Fertilization and meiosis alternate in sexual life cycles
13.3 Meiosis reduces the number of chromosome sets from diploid to haploid
13.4 Genetic variation produced in sexual life cycles contributes to evolution
KEY CONCEPTS
12.1 Most cell division results in genetically identical daughter cells
12.2 The mitotic phase alternates with interphase in the cell cycle
12.3 The eukaryotic cell cycle is regulated by a molecular
control system
KEY CONCEPTS
45.1 Hormones and other signaling molecules bind to target
receptors, triggering specific response pathways
45.2 Feedback regulation and coordination with the nervous system are common in endocrine signaling
45.3 Endocrine glands respond to diverse stimuli in regulating homeostasis, development,
and behavior
KEY CONCEPTS
11.1 External signals are converted to responses within the cell
11.2 Reception: A signaling molecule binds to a receptor protein, causing it to change shape
11.3 Transduction: Cascades of molecular interactions relay
signals from receptors to target molecules in the cell
11.4 Response: Cell signaling leads to regulation of transcription or cytoplasmic activities
11.5 Apoptosis integrates multiple cell-signaling pathways
KEY CONCEPTS
10.1 Photosynthesis converts light energy to the chemical energy of food
10.2 The light reactions convert solar energy to the chemical energy of ATP and NADPH
10.3 The Calvin cycle uses the chemical energy of ATP and NADPH to reduce CO2 to sugar
10.4 Alternative mechanisms of carbon fixation have evolved in hot, arid climates
Chapter 50: Sensory and Motor MechansimsAngel Vega
KEY CONCEPTS
50.1 Sensory receptors transduce stimulus energy and transmit signals to the central nervous system
50.2 The mechanoreceptors responsible for hearing and
equilibrium detect moving fluid or settling particles
50.3 The diverse visual receptors of animals depend on light-
absorbing pigments
50.4 The senses of taste and smell rely on similar sets of sensory receptors
50.5 The physical interaction of protein filaments is required for muscle function
50.6 Skeletal systems transform muscle contraction into
locomotion
KEY CONCEPTS
48.1 Neuron structure and organization reflect function in information transfer
48.2 Ion pumps and ion channels establish the resting potential of a neuron
48.3 Action potentials are the signals conducted by axons
48.4 Neurons communicate with other cells at synapses
KEY CONCEPTS
9.1 Catabolic pathways yield energy by oxidizing organic
fuels
9.2 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate
9.3 After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules
9.4 During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis
9.5 Fermentation and anaerobic respiration enable cells to
produce ATP without the use of oxygen
9.6 Glycolysis and the citric acid cycle connect to many other metabolic pathways
KEY CONCEPTS
7.1 Cellular membranes are fluid mosaics of lipids and proteins
7.2 Membrane structure results in selective permeability
7.3 Passive transport is diffusion of a substance across a
membrane with no energy investment
7.4 Active transport uses energy to move solutes against their gradients
7.5 Bulk transport across the plasma membrane occurs by exocytosis and endocytosis
KEY CONCEPTS
6.1 Biologists use microscopes and the tools of biochemistry to
study cells
6.2 Eukaryotic cells have internal membranes that
compartmentalize their functions
6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
6.4 The endomembrane system regulates protein traffic and
performs metabolic functions in the cell
6.5 Mitochondria and chloroplasts change energy from one form to another
6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell
6.7 Extracellular components and connections between cells help coordinate cellular activities
KEY CONCEPTS
5.1 Macromolecules are polymers, built from monomers
5.2 Carbohydrates serve as fuel and building material
5.3 Lipids are a diverse group of hydrophobic molecules
5.4 Proteins include a diversity of structures, resulting in a wide range of functions
5.5 Nucleic acids store, transmit, and help express hereditary
information
5.6 Genomics and proteomics have transformed biological inquiry and applications
KEY CONCEPTS
4.1 Organic chemistry is the study of carbon compounds
4.2 Carbon atoms can form diverse molecules by bonding to four other atoms
4.3 A few chemical groups are key to molecular function
Bio chapter 2: A Chemical Connection to BiologyAngel Vega
KEY CONCEPTS
2.1 Matter consists of chemical elements in pure form and
in combinations called compounds
2.2 An element’s properties depend on the structure of its atoms
2.3 The formation and function of molecules depend on chemical bonding between atoms
2.4 Chemical reactions make and break chemical bonds
Bio chapter 1 biochemistry, the cell, & geneticsAngel Vega
Evolution, the Themes of Biology, and Scientific Inquiry

KEY CONCEPTS
1.1 The study of life reveals common themes
1.2 The Core Theme: Evolution accounts for the unity and
diversity of life
1.3 In studying nature, scientists make observations and form and test hypotheses
1.4 Science benefits from a cooperative approach and
diverse viewpoints
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
2. Overview: The Energy of Life
• The living cell is a miniature chemical factory
where thousands of reactions occur
• The cell extracts energy and applies energy to
perform work
• Some organisms even convert energy to light,
as in bioluminescence
• Metabolism is the totality of an organism’s
chemical reactions
• Metabolism is an emergent property of life that
arises from interactions between molecules
within the cell
3. Enzyme 1
A B
Reaction 1
Enzyme 2
C
Reaction 2
Enzyme 3
D
Reaction 3
ProductStarting
molecule
•A metabolic pathway begins with a specific molecule and ends with a product
•Each step is catalyzed by a specific enzyme
6. Forms of Energy
• Energy is the capacity to cause change
• Energy exists in various forms, some of which
can perform work
• Bioenergetics is the study of how organisms
manage their energy resources
7. • Kinetic energy is energy associated with motion
– Heat (thermal energy) is kinetic energy associated with random
movement of atoms or molecules
• Potential energy is energy that matter possesses because
of its location or structure
– Chemical energy is potential energy available for release in a
chemical reaction
• Energy can be converted from one form to another
• Solar energy
– Light energy can be converted to chemical energy by
photosynthesis
8. On the platform,
the diver has
more potential
energy.
Diving converts
potential
energy to
kinetic energy.
Climbing up converts
kinetic energy of
muscle movement to
potential energy.
In the water, the
diver has less
potential energy.
Add solar, potential, &
chemical energy for this
picture.
9. The Laws of Energy
Transformation
• Thermodynamics is the study of energy
transformations
• A closed system, such as that approximated by
liquid in a thermos, is isolated from its
surroundings
• In an open system, energy and matter can be
transferred between the system and its
surroundings
• Organisms are open systems
10. The First Law of Thermodynamics
• According to the first law of thermodynamics, the energy of the
universe is constant
– Energy can be transferred and transformed
– Energy cannot be created or destroyed
• The first law is also called the principle of conservation of energy
The Second Law of Thermodynamics
• During every energy transfer or transformation, some energy is
unusable, often lost as heat
• According to the second law of thermodynamics, every energy
transfer or transformation increases the entropy (disorder) of the
universe
11. Chemical
energy
Heat CO2
First law of thermodynamics Second law of thermodynamics
H2O
•Living cells unavoidably convert organized forms
of energy to heat
•Spontaneous processes occur without energy
input; they can happen quickly or slowly (very
slowly in order to get over EA)
•For a process to occur without energy input, it
must increase the entropy of the universe
12. Biological Order and Disorder
• Cells create ordered structures from less
ordered materials
• Organisms also replace ordered forms of
matter and energy with less ordered forms
• The evolution of more complex organisms does
not violate the second law of thermodynamics
• Entropy (disorder) may decrease in an
organism, but the universe’s total entropy
increases
13. • The change in free energy (∆G) during a
process is related to the change in enthalpy, or
change in total energy (∆H), and change in
entropy (T∆S):
∆G = ∆H - T∆S
• Energy in reactions with a negative ∆G can be
harnessed to perform work
• A living system’s free energy is energy that
can do work when temperature and pressure
are uniform, as in a living cell
14. 1. The oxidation of glucose to CO2 and H2O
is highly exergonic: ∆G = −636 kcal/mole.
This is possible, but why is it very slow?
a. Few glucose and oxygen molecules have the
activation energy at room temperature.
b. There is too much CO2 in the air.
c. CO2 has higher energy than glucose.
d. The formation of six CO2 molecules from one
glucose molecule decreases entropy.
e. The water molecules quench the reaction.
15. 1. The oxidation of glucose to CO2 and H2O
is highly exergonic: ∆G = −636 kcal/mole.
This is possible, but why is it very slow?
a. Few glucose and oxygen molecules have
the activation energy at room temperature.
b. There is too much CO2 in the air.
c. CO2 has higher energy than glucose.
d. The formation of six CO2 molecules from one
glucose molecule decreases entropy.
e. The water molecules quench the reaction.
17. Change in Free Energy
• Free energy of the products – free energy
of reactants = negative, then products
have a greater stability than reactants
• Products have less free energy; in open
system, must include environment
• An exergonic reaction proceeds with a net
release of free energy
• An endergonic reaction absorbs free energy
from its surroundings and reactants are more
stable than products
20. 2. Firefly luciferase catalyzes the following reaction:
luciferin + ATP ↔ adenyl-luciferin + pyrophosphate
Then the next reaction occurs spontaneously:
adenyl-luciferin + O2 → oxyluciferin + H2O + CO2 + AMP + light
What is the role of luciferase?
a. Luciferase makes the ∆G of the reaction more
negative.
b. Luciferase produces a transition state with a
lower free energy
c. Luciferase alters the equilibrium point of the
reaction.
d. Luciferase makes the reaction irreversible.
e. Luciferase creates a phosphorylated
intermediate.
21. 2. Firefly luciferase catalyzes the following reaction:
luciferin + ATP ↔ adenyl-luciferin + pyrophosphate
Then the next reaction occurs spontaneously:
adenyl-luciferin + O2 → oxyluciferin + H2O + CO2 + AMP + light
What is the role of luciferase?
a. Luciferase makes the ∆G of the reaction more
negative.
b. Luciferase produces a transition state with a
lower free energy.
c. Luciferase alters the equilibrium point of the
reaction.
d. Luciferase makes the reaction irreversible.
e. Luciferase creates a phosphorylated
intermediate.
22. Equilibrium and Metabolism
• Reactions in a closed system eventually reach
equilibrium and then do no work
• Cells are not in equilibrium; they are open
systems experiencing a constant flow of
materials
• A catabolic pathway in a cell releases free
energy in a series of reactions
• Closed and open hydroelectric systems can
serve as analogies
23. LE 8-7a
∆G = 0
A closed hydroelectric system
∆G < 0
26. Concept 8.3: ATP powers cellular
work by coupling exergonic
reactions to endergonic reactions
• A cell does three main kinds of work:
– Mechanical
– Transport
– Chemical
• To do work, cells manage energy resources by
energy coupling, the use of an exergonic
process to drive an endergonic one
28. • The bonds between the phosphate groups of
ATP’s tail can be broken by hydrolysis
• Energy is released from ATP when the terminal
phosphate bond is broken
• This release of energy comes from the
chemical change to a state of lower free
energy, not from the phosphate bonds
themselves
30. • In the cell, the energy from the exergonic
reaction of ATP hydrolysis can be used to
drive an endergonic reaction
• Overall, the coupled reactions are exergonic
31. LE 8-10
Endergonic reaction: ∆G is positive, reaction
Requires input of energy
Exergonic reaction: ∆G is negative, products have
less free energy than reactants
∆G = +3.4 kcal/mol
∆G = –7.3 kcal/mol
∆G = –3.9 kcal/mol
NH2
NH3
Glu Glu
Glutamic
acid
Coupled reactions: Overall ∆G is negative;
together, reactions give off heat
Ammonia Glutamine
ATP H2O ADP P i
+
+ +
32. How ATP Performs Work
• ATP drives endergonic reactions by
phosphorylation, transferring a phosphate
group to some other molecule, such as a
reactant
• The recipient molecule is now phosphorylated
• The three types of cellular work (mechanical,
transport, and chemical) are powered by the
hydrolysis of ATP
33. LE 8-11
NH2
Glu
P i
P i
P i
P i
Glu
NH3
P
P
P
ATP
ADP
Motor protein
Mechanical work: ATP phosphorylates motor proteins
Protein moved
Membrane
protein
Solute
Transport work: ATP phosphorylates transport proteins
Solute transported
Chemical work: ATP phosphorylates key reactants
Reactants: Glutamic acid
and ammonia
Product (glutamine)
made
+ +
+
34. P
i
ADP
Energy for cellular work
(endergonic, energy-
consuming processes)
Energy from catabolism
(energonic, energy-
yielding processes)
ATP
+
The Regeneration of ATP
•ATP is a renewable resource that is regenerated by addition of a
phosphate group to ADP
•The energy to phosphorylate ADP comes from catabolic reactions
in the cell
•The chemical potential energy temporarily stored in ATP drives
most cellular work
35. Enzymes speed up metabolic
reactions by providing an alternative
pathway with a lower EA
• A catalyst is a chemical agent that speeds up a
reaction without being consumed by the
reaction
• An enzyme is a catalytic protein or RNA
• Hydrolysis of sucrose by the enzyme sucrase
is an example of an enzyme-catalyzed reaction
37. The Activation Energy Barrier
• Every chemical reaction between molecules
involves bond breaking and bond forming
• The initial energy needed to start a chemical
reaction is called the free energy of activation,
or activation energy (EA)
• Activation energy is often supplied in the form
of heat from the surroundings
38. LE 8-14
Transition state
C D
A B
EA
Products
C D
A B
∆G < O
Progress of the reaction
Reactants
C D
A B
Freeenergy
39. How Enzymes Lower the EA
Barrier
• Enzymes catalyze reactions by lowering the
EA barrier—provide an alternative transition
state
• Enzymes do not affect the change in free-
energy (∆G); instead, they hasten reactions
that could occur eventually
40. 3. In the energy diagram below, which of the
energy changes would be the same in both the
enzyme-catalyzed and uncatalyzed reactions?
a
b
c
d
e
41. 3. In the energy diagram below, which of the
energy changes would be the same in both the
enzyme-catalyzed and uncatalyzed reactions?
a
b
c
d
e
43. Substrate Specificity of
Enzymes
• The reactant that an enzyme acts on is called
the enzyme’s substrate
• The enzyme binds to its substrate, forming an
enzyme-substrate complex
• The active site is the region on the enzyme
where the substrate binds
• Induced fit of a substrate brings chemical
groups of the active site into positions that
enhance their ability to catalyze the reaction
44. LE 8-16
Substrate
Active site
Enzyme Enzyme-substrate
complex
If reversible, what are the possible types of bonds utilized
by enzymes in their active sites?
45. Catalysis in the Enzyme’s
Active Site
• In an enzymatic reaction, the substrate binds to
the active site
• The active site can lower an EA barrier by
– Orienting substrates correctly
– Straining substrate bonds
– Providing a favorable microenvironment
– Covalently bonding to the substrate
46. LE 8-17
Enzyme-substrate
complex
Substrates
Enzyme
Products
Substrates enter active site; enzyme
changes shape so its active site
embraces the substrates (induced fit).
Substrates held in
active site by weak
interactions, such as
hydrogen bonds and
ionic bonds.
Active site (and R groups of
its amino acids) can lower EA
and speed up a reaction by
• acting as a template for
substrate orientation,
• stressing the substrates
and stabilizing the
transition state,
• providing a favorable
microenvironment,
• participating directly in the
catalytic reaction.
Substrates are
converted into
products.
Products are
released.
Active
site is
available
for two new
substrate
molecules.
47. Effects of Local Conditions on
Enzyme Activity
• An enzyme’s activity can be affected by:
– General environmental factors, such as
temperature and pH
– Chemicals that specifically influence the
enzyme
• Each enzyme has an optimal temperature in
which it can function
• Each enzyme has an optimal pH in which it
can function
We can find these in lab the next few weeks!
48. LE 8-18
Optimal temperature for
typical human enzyme
Optimal temperature for
enzyme of thermophilic
(heat-tolerant
bacteria)
Temperature (°C)
Optimal temperature for two enzymes
0 20 40 60 80 100
Rateofreaction
Optimal pH for pepsin
(stomach enzyme)
Optimal pH
for trypsin
(intestinal
enzyme)
pH
Optimal pH for two enzymes
0
Rateofreaction
1 2 3 4 5 6 7 8 9 10
Explain what is
happening at each
section of the curve.
49.
50. Cofactors
• Cofactors are nonprotein enzyme helpers
• Coenzymes are organic cofactors
Enzyme Inhibitors
• Competitive inhibitors bind to the active site of
an enzyme, competing with the substrate
• Noncompetitive inhibitors bind to another part
of an enzyme, causing the enzyme to change
shape and making the active site less effective
51. LE 8-19
Substrate
Active site
Enzyme
Competitive
inhibitor
Normal binding
Competitive inhibition
Noncompetitive inhibitor
Noncompetitive inhibition
A substrate can
bind normally to the
active site of an
enzyme.
A competitive
inhibitor mimics the
substrate, competing
for the active site.
A noncompetitive
inhibitor binds to the
enzyme away from the
active site, altering the
conformation of the
enzyme so that its
active site no longer
functions.
52. Concept 8.5: Regulation of
enzyme activity helps control
metabolism
• Chemical chaos would result if a cell’s
metabolic pathways were not tightly regulated
• To regulate metabolic pathways, the cell
switches on or off the genes that encode
specific enzymes
53. Allosteric Regulation of
Enzymes
• Allosteric regulation is the term used to
describe cases where a protein’s function at
one site is affected by binding of a regulatory
molecule at another site
• Allosteric regulation may either inhibit or
stimulate an enzyme’s activity
54. Allosteric Activation and
Inhibition
• Most allosterically regulated enzymes are
made from polypeptide subunits
• Each enzyme has active and inactive forms
• The binding of an activator stabilizes the active
form of the enzyme
• The binding of an inhibitor stabilizes the
inactive form of the enzyme
55. LE 8-20a
Allosteric enzyme
with four subunits
Regulatory
site (one
of four) Active form
Activator
Stabilized active form
Active site
(one of four)
Allosteric activator
stabilizes active form.
Non-
functional
active site
Inactive form
Inhibitor
Stabilized inactive
form
Allosteric inhibitor
stabilizes inactive form.
Oscillation
Allosteric activators and inhibitors
56. • Cooperativity is a form of allosteric regulation
that can amplify enzyme activity
• In cooperativity, binding by a substrate to one
active site stabilizes favorable conformational
changes at all other subunits
57. LE 8-20b
Substrate
Binding of one substrate molecule to
active site of one subunit locks all
subunits in active conformation.
Cooperativity another type of allosteric activation
Stabilized active formInactive form
59. Lineweaver-Burk analysis is one method of linearizing substrate-velocity data so
as to determine the kinetic constants Km and Vmax. One creates a secondary,
reciprocal plot: 1/velocity vs. 1/[substrate]. When catalytic activity follows
Michaelis-Menten kinetics over the range of substrate concentrations tested, the
Lineweaver-Burk plot is a straight line with
Y intercept = 1/Vmax,
X intercept = -1/Km
slope = Km/Vmax
60. 4. Which choice best describes what the H+
−ATPase does in terms of flow of energy in
many cells?
a. It converts light energy into energy
in a concentration gradient.
b. It converts matter into energy in the
form of an electrochemical
gradient.
c. It pumps protons up their pressure
gradient.
d. It converts chemical energy to
energy in an electrochemical
gradient and heat.
e. It converts energy in a
concentration gradient
to energy in an electrical gradient.
61. 4. Which choice best describes what the H+
−ATPase does in terms of flow of energy in
many cells?
a. It converts light energy into energy
in a concentration gradient.
b. It converts matter into energy in the
form of an electrochemical
gradient.
c. It pumps protons up their pressure
gradient.
d. It converts chemical energy to
energy in an electrochemical
gradient and heat.
e. It converts energy in a
concentration gradient
to energy in an electrical gradient.
62. Feedback Inhibition
• In feedback inhibition, the end product of a
metabolic pathway shuts down the pathway
• Feedback inhibition prevents a cell from
wasting chemical resources by synthesizing
more product than is needed
63. LE 8-21
Active site
available
Initial substrate
(threonine)
Threonine
in active site
Enzyme 1
(threonine
deaminase)
Enzyme 2
Intermediate A
Isoleucine
used up by
cell
Feedback
inhibition Active site of
enzyme 1 can’t
bind
theonine
pathway off
Isoleucine
binds to
allosteric
site
Enzyme 3
Intermediate B
Enzyme 4
Intermediate C
Enzyme 5
Intermediate D
End product
(isoleucine)
64. Specific Localization of
Enzymes Within the Cell
• Structures within the cell help bring order to
metabolic pathways
• Some enzymes act as structural components
of membranes (oxidative phosphorylation in
Ch.9; photsynthetic phosphorylation in Ch.10)
• Some enzymes reside in specific organelles,
such as enzymes for cellular respiration being
located in mitochondria— next chapter