This document summarizes key concepts about metabolism, including: 1) Metabolism involves both anabolic and catabolic reactions that synthesize and break down molecules. ATP is the main energy currency molecule in cells. 2) Glycolysis, the citric acid cycle, and electron transport chain are the main catabolic pathways that break down glucose and other fuels to generate ATP through cellular respiration. 3) Dehydration synthesis and hydrolysis are important reaction types in metabolism. Enzymes catalyze metabolic reactions and are essential for metabolic pathways and cellular function.

1. Metabolism
Chapter 4
ivyanatomy.com
Anatomy & Physiology

2. Metabolism is the sum of all reactions in the body
Anabolism
Synthesize larger molecules
from smaller ones.
Cells use energy
Decomposes larger molecules
into smaller ones.
Releases energy for cellular use
Catabolism
Cellular Metabolism

3. Glucose molecules are joined by
dehydration synthesis
Most polymers are synthesized through dehydration synthesis.
Anabolic Reactions
Dehydration Synthesis
A water molecule is released to join molecules together.
+ +
H2O

4. Dehydration synthesis synthesizes polysaccharides, fats,
proteins, and nucleic acids from their monomers.
Several Monomers Polymer
+ H2O
Dehydration Synthesis

5. Dehydration Synthesis
Dehydration synthesis of a polysaccharide.
Amylose is a polysaccharide composed of
several thousand glucose monosaccharides.
+ H2O
glucose

6. Dehydration Synthesis
Dehydration synthesis of a triglyceride.
+ H2O

7. Dehydration Synthesis
Dehydration synthesis of a polypeptide.
+ H2O

8. S
CH2
B
P OO
OH
O
OH
Dehydration Synthesis
Dehydration synthesis of a polynucleotide.
S
CH2
B
P OO
OH
O
OH
S
CH2
B
P OO
O
O
OH
S
CH2
B
P OO
OH
O
+ H2O

9. Water is consumed to break apart the molecules
hydrolysis is the reverse of dehydration synthesis
hydrolysis releases energy from chemical bonds
Hydrolysis
++
H2O

10. Hydrolysis is used to decompose polysaccharides, fats, proteins, and
nucleic acids into their monomers.
Several MonomersPolymer
+ H2O
Hydrolysis

11. Hydrolysis
Hydrolysis of a polysaccharide.
Water is added to amylose, which decomposes into glucose molecules
+ H2O
glucose

12. ++ H2O
Hydrolysis
Hydrolysis of a triglyceride (fat).

13. Hydrolysis
Hydrolysis of a dipeptide.
+ H2O +

14. S
CH2
B
P OO
OH
O
OH
Hydrolysis
Hydrolysis of a dinucleotide.
S
CH2
B
P OO
O
O
OH
S
CH2
B
P OO
OH
O
+ H2O
S
CH2
B
P OO
OH
O
OH

15. +
Monomers linked by covalent bond
Dehydration Synthesis
Hydrolysis
+
Monomers linked by covalent bond

16. Activation energy
Activation Energy – Amount of energy required to initiate a reaction

17. Activation energy
• A catalyst – increases the rate of the reaction without being
consumed by the reaction
Activation energy
without catalyst
Activation energy
with a catalyst
Catalysts lower the activation energy
required to initiate a reaction
Lower energy state

18. *A substrate is the target molecule of an enzyme
Characteristics of enzymes
• Enzymes lower the activation energy of a reaction
• Most enzymes are proteins
• Enzymes catalyze reactions (they increase the rate of reactions, but are not consumed by the
reaction)
• Enzymes are specific to one substrate*.
• Most enzymes end in ____ase. (lipase, protease, nuclease, ATPase, etc.)
Enzymes

19. Synthesis reaction involving an enzyme
Enzymes catalyze reactions (increases rate), but are
not consumed by the reaction (reusable).
Proteins
Substrates
Active Site Active Site
A B
Enzyme
A
Enzyme-Substrate Complex
B
Product
Active Site Active Site
A B
Enzyme is unchanged

20. The rate of an enzyme-catalyzed reaction is limited by:
1. The concentration of substrate
2. The concentration of enzyme
3. Enzyme efficiency
Measures how efficiently the enzyme converts substrates
into produces
Enzymes

21. A metabolic pathway is a complex series of reactions leading to a product
Metabolic Pathways are controlled by several enzymes
Metabolic Pathways

22. The product of each reaction becomes the substrate of next reaction.
Each step requires its own enzyme
The least efficient enzyme is the “Rate-Limiting Enzyme”
Rate-limiting enzyme is usually first in sequence
• Enzyme A = Rate-limiting Enzyme
Metabolic Pathways
Substrate
1
Substrate
2
Enzyme BEnzyme A Substrate
3
Enzyme C Substrate
4
Enzyme D Product

23. Negative feedback prevents too much product from being produced.
The product of the metabolic pathway often inhibits the rate-limiting enzyme.
Negative Feedback in Metabolic Pathway
Substrate
1
Substrate
2
Enzyme BEnzyme A Substrate
3
Enzyme C Substrate
4
Enzyme D Product
Rate-limiting

24. Cofactor
substance that increases the efficiency of an enzyme
Cofactors include ions (zinc, iron, copper) and coenzymes
Coenzymes are organic cofactors
Coenzymes include Vitamins (Vitamin A, B, D)
Reusable – required in small amounts
Enzymes

25. Vitamins are essential organic molecules that humans cannot synthesize, so they
must come from diet
Many vitamins are coenzymes
Vitamins can function repeatedly, so can be used in small amounts.
Example: Coenzyme A
Enzymes

26. Energy: is the capacity to change something, or ability to do work.
Common forms of energy:
Heat
Radiant (light)
Sound
Chemical
Mechanical
Electrical
Energy

27. Conservation of Energy:
Energy can be converted from one form to another,
but it cannot be created or destroyed.
Energy

28. Energy
Examples of transferring energy:
Automobile energy converts
chemical energy into
mechanical and heat energy
Lightbulb converts electrical
energy into radiant (light)
energy and heat energy
Tree converts radiant (light)
energy from the sun into
chemical energy.

30. Energy from foods such as glucose is used to make ATP for the cell.
Initial fuel or
energy source
ATP = Energy
currency for cells
Cellular Respiration
Cell Respiration is the transfer of energy
from food molecules into a form the cells
can use

31. adenine ribose
P P P
Adenosine Triphosphate
ATP
ATP (Adenosine Triphosphate) carries energy in a form the cell can use
Main energy-carrying molecule in the cell; energy from ATP breakdown is
used for cellular work
ATP Molecules

32. Energy released
for cell activity
Hydrolysis of ATP

33. +
Energy released
for metabolism
Energy invested
from respiration

34. • Many metabolic processes require chemical energy, which is
stored in ATP
• Energy is held in chemical bonds, and released when bonds
are broken
• Oxidation releases energy from glucose
• Energy is then used to power cellular metabolism
• In cells, enzymes initiate oxidation by lowering activation
energy
• Energy is transferred to ATP:
40% is released as chemical energy
60% is released as heat; maintains body temperature
34
Release of Chemical Energy

35. + +
Oxidation releases energy from glucose
Overview of Cell Respiration
Oxidation – transfer of electrons to a final electron acceptor.
Glucose (C6H12O6) 6 O2+ 6 CO2 6 H2O+

36. Release of Chemical Energy
Oxidation of glucose releases energy that is use to produce new ATP
Energy is transferred to ATP:
40% is captured to produce ATP
60% is released as heat
C6H12O6
(Glucose)
6 O2+ 6 CO2 6 H2O+ + Energy

37. Overview of Cell Respiration
1. Glycolysis 2. Citric Acid Cycle 3. Electron Transport Chain
Lactic Acid
oxygen present
(aerobic respiration)
oxygen not present
(anaerobic respiration)
Glucose (C6H12O6)

38. Electron Carriers
(NADH & FADH2)
NAD+
+ 2 NAD H
-e -e
H
+
+
+ 2 FADH
-e
H2
-e -e
+FAD
(each hydrogen has an electron)
H
-e

39. Electron Carriers
(NADH & FADH2)
NADH is worth 3 ATP
FADH2 is worth 2 ATP
Electron Transport Chain
To extract ATP from NADH and
FADH2, the electron carriers must
first be transferred to the ETC

40. Glycolysis
Occurs in cytosol
Anaerobic (no oxygen required)
Yields 2 ATP per glucose

41. Glycolysis
C C C C C C
C C C C C C
1. Phosphorylation
2. Cleavage
3. Oxidation
(next slide)
C C C PC C CP
C C C C C C PP
Glucose (C6H12O6)
ATPATP
ADPADP
2ATP2 ATP
2ADP
2ADP
NAD+
NAD+
NADH
NADH
pyruvate pyruvate

42. C C C C C C
3. Oxidation
pyruvate
PC C CP
pyruvate
2ATP2 ATP
2ADP2ADP
NAD+
NAD+
NADH NADH
Oxygen AvailableNo Oxygen
2. CAC
3. ETC
Lactic Acid
anaerobic respiration aerobic respiration

43. Anaerobic Respiration
C C C
Pyruvate
NAD H
-e -e
NAD+
H
-e -e
C C C+
Lactic Acid

44. Anaerobic Respiration
H
-e -e
C C C
O O
Oxygen debt is the amount of O2 required to convert
the lactic acid back to glucose after exercise.
C C C C C C
Glucose (C6H12O6)
Lactic Acid
oxygen

45. Citric Acid Cycle
&
Electron Transport Chain

46. Glycolysis
C C C C C C
C C C C C C
1. Phosphorylation
2. Cleavage
3. Oxidation
C C C PC C CP
C C C C C C PP
Glucose (C6H12O6)
ATPATP
ADPADP
2ATP2 ATP
2ADP
2ADP
NAD+
NAD+
NADH
NADH
pyruvate pyruvate

47. C C C C C C
3. Oxidation
pyruvate
PC C CP
pyruvate
2ATP2 ATP
2ADP2ADP
NAD+
NAD+
NADH NADH
Oxygen AvailableNo Oxygen
2. CAC
3. ETC
Lactic Acid
anaerobic respiration aerobic respiration

48. mitochondria
Mitochondria are the powerhouse of cell.
Most ATP are synthesized within mitochondria

49. Priming Pyruvic Acid for the Citric Acid Cycle
Before pyruvic acid can enter the CAC it
must first be converted into acetyl CoA
Acetyl CoA is the substrate
for the citric acid cycle.
For each pyruvic acid, this reaction produces
1 CO2 molecule
1 NADH molecule
1 Acetyl CoA
1 molecule of
CO2 is released
NAD+
NADH
acetyl CoA
Coenzyme A
C C C
pyruvate
C C
acetic acid
C C

50. Citric Acid Cycle
The citric acid cycle occurs in the
matrix of the mitochondrion.

51. C C C C
C C
C C C C C C
citric acid
3 NAD+
3 NADH
ADP + PATP
Citric Acid Cycle
FAD
FADH2
2CO2
acetyl CoA
C C C C C C
oxaloacetic acid
Co-Enzyme A is released
C C C C

52. 1 ATP
3 NADH
1 FADH2
2 CO2
Products of the citric acid cycle:

53. Each Glucose = 2 turns of the CAC
glucose
CACCAC
C C C C C C
C C C
pyruvate
C C C
pyruvate
C C
acetyl CoA
C C
acetyl CoA

54. electron transport chain (ETC)
The ETC is located on the inner membrane of mitochondria
An enzyme called ATP synthase forms ATP by attaching a phosphate to ADP
ATP synthase is powered by the transfer of e- along a chain protein complexes that
form the ETC.
ETC

55. The ETC produces 32-34 ATP per glucose
Oxygen removes electrons from the final
complex protein, so it is the final e- acceptor
electron transport chain (ETC)

57. 57
Carbohydrate molecules from foods can:
• Enter catabolic pathways for energy production
• Enter anabolic pathways for energy storage
• React to form some of the amino acids
Excess glucose can be converted
into and stored as:
• Glycogen: Most cells, but liver
and muscle cells store the most
• Fat to store in adipose tissue
Carbohydrate Metabolism

58. Carbohydrates, Lipids & Proteins can be
broken down and used for ATP synthesis
Most organic molecules enter the
citric acid cycle as acetyl coA
catabolism of proteins, fats, & carbohydrates

59. DNA Replication & Protein Synthesis
Chapter 4.6

60. nucleus cytoplasm

61. nucleus cytoplasm

62. Definitions
Gene: portion of DNA that encodes one protein
Genome: complete set of genetic instructions for an organism
Human genome = 20,000 genes on 46 chromosomes

63. Genetic (triplet) code:
3 letter DNA sequence that encodes for 1 amino acid

64. Double-stranded helix

66. • Anti-parallel
• The sugar in DNA is deoxyribose
• Sugar-phosphate backbone
• 4 Nitrogenous Bases
Deoxyribonucleic Acid (RNA)
Hydrogen bonds

67. Purines
Adenine & Guanine
Pyrimidines
Thymine & Cytosine
DNA contains 4 nitrogenous bases
Adenine (A) Thymine (T)
Guanine (G) Cytosine (C)
Properties of DNA

68. Complimentary Base Pairs

69. Example of complimentary base pairs.

71. S Phase
DNA Replication

72. DNA replication is catalyzed by the
enzyme DNA Polymerase
DNA Replication

73. DNA Replication

74. Replication Fork

75. Replication Fork

76. DNA replication is Semi-Conservative –
One strand of the replicated DNA is new,
the other is the original molecule.
DNA Replication

77. The two DNA molecules separate during mitosis

78. Chapter 4.7
Transcription & Translation

81. 81
There are several kinds of RNA
Transfer RNA (tRNA):
Transfers amino acids to the ribosomes during translation.
Ribosomal RNA (rRNA):
Provides structure and enzyme activity for ribosomes
Messenger RNA (mRNA):
Conveys genetic information from DNA to the ribosomes

82. • mRNA undergoes further processing & leaves the nucleus

83. Codon: 3 letter mRNA sequence that encodes for 1 amino acid.
start codon: Initiates protein synthesis (AUG = start codon)
stop codon: terminates translation (doesn’t code for an amino acid)

85. 1. transfer RNA (tRNA) transports amino acid to mRNA
2. anticodon on tRNA aligns with codon on mRNA
tRNA
1 Amino acid

86. Ribosomes
1
Amino acid
codoncodon

88. A U G
ribosome
U A C
1
2
3
tRNA
Amino acid

89. A U G
2
3
U A C
1
tRNA

90. A U G
U A C
1
2
3

91. A U G
U A C
1
2
3
peptide bond

92. A U G
U A C
1
2
3
peptide bond

93. A U G
U A C
3
1
2
peptide bond
4
5

94. A U G
U A C
3
1
2
peptide bond
4
5

95. A U G
3
1
2
peptide bond
4
5

96. A U G
3
1
2
peptide bond
4
5

97. A U G
3
1
2
peptide bond
4
5

98. A U G
1
2
peptide bond
6
3 4 5

99. A U G
1
2
peptide bond
63 4 5
7

100. STOP
CODON
AGU

101. STOP
CODON
AGU
Polypeptide chain

102. Once translation is complete chaperone proteins
fold the protein into its configuration
enzymes may further modify proteins after translation
phosphorylation – adding a phosphate to the protein
glycosylation – adding a sugar to the protein
post-translational modification
End of Chapter 4

103. Attribution
• Protein By Emw (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL
(http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons.
https://upload.wikimedia.org/wikipedia/commons/1/10/Protein_NP_PDB_1m73.png
• Triglyceride By Wolfgang Schaefer (author) [Public domain], via Wikimedia Commons.
https://upload.wikimedia.org/wikipedia/commons/b/be/Fat_triglyceride_shorthand_formula.PNG
• "Amylose 3Dprojection.corrected" by glycoform - Own work. Licensed under Public Domain via Commons -
https://commons.wikimedia.org/wiki/File:Amylose_3Dprojection.corrected.png#/media/File:Amylose_3Dprojection.corr
ected.png
• "Beta-D-Glucose" by Yikrazuul - Own work. Licensed under Public Domain via Commons -
https://commons.wikimedia.org/wiki/File:Beta-D-Glucose.svg#/media/File:Beta-D-Glucose.svg
• "Isomers of oleic acid" by Edgar181 - Own work. Licensed under Public Domain via Commons -
https://commons.wikimedia.org/wiki/File:Isomers_of_oleic_acid.png#/media/File:Isomers_of_oleic_acid.png
• By Fir0002 [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-
sa/3.0/)], via Wikimedia Commons. https://upload.wikimedia.org/wikipedia/commons/3/36/Large_bonfire.jpg
• "Molecular-collisions" by Sadi_Carnot - http://en.wikipedia.org/wiki/Image:Molecular-collisions.jpg. Licensed under
Public Domain via Commons - https://commons.wikimedia.org/wiki/File:Molecular-collisions.jpg#/media/File:Molecular-
collisions.jpg
• Metabolic Pathways
https://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Metabolism_pathways_(partly_labeled).svg/2000px-
Metabolism_pathways_(partly_labeled).svg.png
• Genetic Code By Madprime (Own work) [CC0, GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0
(http://creativecommons.org/licenses/by-sa/3.0/) or CC BY-SA 2.5-2.0-1.0 (http://creativecommons.org/licenses/by-