1. Chapter 5
Microbial Metabolism

2. Catabolic and Anabolic Reactions
Metabolism: The sum of the chemical reactions in an organism

3. Catabolic and Anabolic Reactions
Catabolism: Provides energy and building blocks for anabolism.
Anabolism: Uses energy and building blocks to build large molecules

4. Role of ATP in Coupling Reactions
Figure 5.1

5. Catabolic and Anabolic Reactions
A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell
Metabolic pathways are determined by enzymes
Enzymes are encoded by genes
ANIMATION Metabolism: Overview

6. Collision Theory
The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide
Activation energy is needed to disrupt electronic configurations
Reaction rate is the frequency of collisions with enough energy to bring about a reaction.
Reaction rate can be increased by enzymes or by increasing temperature or pressure

7. Energy Requirements of a Chemical Reaction
Figure 5.2

8. Enzyme Components Biological catalysts Apoenzyme: Protein
Specific for a chemical reaction; not used up in that reaction
Apoenzyme: Protein
Cofactor: Nonprotein component
Coenzyme: Organic cofactor
Holoenzyme: Apoenzyme plus cofactor

9. Components of a Holoenzyme
Figure 5.3

10. Important Coenzymes
NAD+
NADP+
FAD
Coenzyme A

11. Enzyme Specificity and Efficiency
The turnover number is generally 1 to 10,000 molecules per second
ANIMATION Enzymes: Steps in a Reaction
ANIMATION Enzymes: Overview

12. The Mechanism of Enzymatic Action
Figure 5.4a

13. The Mechanism of Enzymatic Action
Figure 5.4b

14. Enzyme Classification
Oxidoreductase: Oxidation-reduction reactions
Transferase: Transfer functional groups
Hydrolase: Hydrolysis
Lyase: Removal of atoms without hydrolysis
Isomerase: Rearrangement of atoms
Ligase: Joining of molecules, uses ATP

15. Factors Influencing Enzyme Activity
Temperature pH
Substrate concentration
Inhibitors

16. Factors Influencing Enzyme Activity
Temperature and pH denature proteins
Figure 5.6

17. Effect of Temperature on Enzyme Activity
Figure 5.5a

18. Effect of pH on Enzyme Activity
Figure 5.5b

19. Effect of Substrate Concentration on Enzyme Activity
Figure 5.5c

20. Enzyme Inhibitors: Competitive Inhibition
Figure 5.7a–b

21. Enzyme Inhibitors: Competitive Inhibition
ANIMATION Competitive Inhibition

22. Enzyme Inhibitors: Noncompetitive Inhibition
ANIMATION Non-competitive Inhibition
Figure 5.7a, c

23. Enzyme Inhibitors: Feedback Inhibition
Figure 5.8

24. Ribozymes
RNA that cuts and splices RNA

25. Oxidation-Reduction Reactions
Oxidation: Removal of electrons
Reduction: Gain of electrons
Redox reaction: An oxidation reaction paired with a reduction reaction

26. Oxidation-Reduction
Figure 5.9

27. Oxidation-Reduction Reactions
In biological systems, the electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations.
ANIMATION Oxidation-Reduction Reactions

28. Representative Biological Oxidation
Figure 5.10

29. The Generation of ATP
ATP is generated by the phosphorylation of ADP

30. Substrate-Level Phosphorylation
Energy from the transfer of a high-energy PO4– to ADP generates ATP

31. Oxidative Phosphorylation
Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain

32. Photophosphorylation
Light causes chlorophyll to give up electrons. Energy released from transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP.

33. Metabolic Pathways of Energy Production

34. Carbohydrate Catabolism
The breakdown of carbohydrates to release energy
Glycolysis
Krebs cycle
Electron transport chain

35. Glycolysis
The oxidation of glucose to pyruvic acid produces ATP and NADH
Figure 5.11

36. Preparatory Stage of Glycolysis
2 ATP are used
Glucose is split to form 2 glucose-3-phosphate
Figure 5.12, steps 1–5

37. Energy-Conserving Stage of Glycolysis
2 glucose-3-phosphate oxidized to 2 pyruvic acid
4 ATP produced
2 NADH produced
Figure 5.12, steps 6–10

38. Glycolysis
Glucose + 2 ATP + 2 ADP + 2 PO4– + 2 NAD+  2 pyruvic acid + 4 ATP + 2 NADH + 2H+
ANIMATION Glycolysis: Steps
ANIMATION Glycolysis: Overview

39. Alternatives to Glycolysis
Pentose phosphate pathway
Uses pentoses and NADPH
Operates with glycolysis
Entner-Doudoroff pathway
Produces NADPH and ATP
Does not involve glycolysis
Pseudomonas, Rhizobium, Agrobacterium

40. Cellular Respiration
Oxidation of molecules liberates electrons for an electron transport chain
ATP is generated by oxidative phosphorylation

41. Intermediate Step
Pyruvic acid (from glycolysis) is oxidized and decarboyxlated
Figure 5.13

42. The Krebs Cycle Oxidation of acetyl CoA produces NADH and FADH2
ANIMATION Krebs Cycle: Steps
ANIMATION Krebs Cycle: Overview

43. The Krebs Cycle
Figure 5.13

44. The Electron Transport Chain
A series of carrier molecules that are, in turn, oxidized and reduced as electrons are passed down the chain
Energy released can be used to produce ATP by chemiosmosis
ANIMATION Electron Transport Chain: Overview

45. Overview of Respiration and Fermentation
Figure 5.11

46. Chemiosmotic Generation of ATP
Figure 5.16

47. An Overview of Chemiosmosis
ANIMATION Electron Transport Chain: The Process
Figure 5.15

48. A Summary of Respiration
Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O2).
Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycles operates under anaerobic conditions.

49. Respiration
ANIMATION Electron Transport Chain: Factors Affecting ATP Yield
Figure 5.16

50. Anaerobic Respiration
Electron Acceptor
Products
NO3–
NO2–, N2 + H2O
SO4–
H2S + H2O
CO32 –
CH4 + H2O

51. Carbohydrate Catabolism
Pathway
Eukaryote
Prokaryote
Glycolysis
Cytoplasm
Intermediate step
Krebs cycle
Mitochondrial matrix
ETC
Mitochondrial inner membrane
Plasma membrane

52. Carbohydrate Catabolism
Energy produced from complete oxidation of one glucose using aerobic respiration
Pathway
ATP Produced
NADH Produced
FADH2 Produced
Glycolysis 2
Intermediate step
Krebs cycle 6
Total 4 10

53. Carbohydrate Catabolism
ATP produced from complete oxidation of one glucose using aerobic respiration
Pathway
By Substrate-Level Phosphorylation
By Oxidative Phosphorylation
From NADH
From FADH
Glycolysis 2 6
Intermediate step
Krebs cycle 18 4
Total 30

54. Carbohydrate Catabolism
36 ATPs are produced in eukaryotes
Pathway
By Substrate-Level Phosphorylation
By Oxidative Phosphorylation
From NADH
From FADH
Glycolysis 2 6
Intermediate step
Krebs cycle 18 4
Total 30

55. Fermentation Any spoilage of food by microorganisms (general use)
Any process that produces alcoholic beverages or acidic dairy products (general use)
Any large-scale microbial process occurring with or without air (common definition used in industry)

56. Fermentation Scientific definition:
Releases energy from oxidation of organic molecules
Does not require oxygen
Does not use the Krebs cycle or ETC
Uses an organic molecule as the final electron acceptor

57. An Overview of Fermentation
ANIMATION Fermentation
Figure 5.18a

58. End-Products of Fermentation
Figure 5.18b

59. Fermentation Alcohol fermentation: Produces ethanol + CO2
Lactic acid fermentation: Produces lactic acid
Homolactic fermentation: Produces lactic acid only
Heterolactic fermentation: Produces lactic acid and other compounds

60. Types of Fermentation
Figure 5.19

61. A Fermentation Test
Figure 5.23

62. Types of Fermentation
Table 5.4

63. Types of Fermentation
Table 5.4

64. Lipid Catabolism
Figure 5.20

65. Catabolism of Organic Food Molecules
Figure 5.21

66. Protein Catabolism Protein Amino acids Organic acid Krebs cycle
Extracellular proteases
Protein
Amino acids
Deamination, decarboxylation, dehydrogenation, desulfurylation
Organic acid
Krebs cycle

67. Protein Catabolism
Decarboxylation
Figure 5.22

68. Protein Catabolism
Desulfurylation
Figure 5.24

69. Protein Catabolism
Urease
Urea
NH3 + CO2
Clinical Focus Figure B

70. Biochemical Tests
Used to identify bacteria.
Clinical Focus Figure A

71. Photosynthesis
Figure 4.15

72. Photosynthesis
Photo: Conversion of light energy into chemical energy (ATP)
Light-dependent (light) reactions
Synthesis:
Carbon fixation: Fixing carbon into organic molecules
Light-independent (dark) reaction: Calvin-Benson cycle
ANIMATION Photosynthesis: Overview

73. Photosynthesis Oxygenic: Anoxygenic:
ANIMATION: Photosynthesis: Comparing Prokaryotes and Eukaryotes

74. Cyclic Photophosphorylation
ANIMATION Photosynthesis: Light Reaction: Cyclic Photophosphorylation
Figure 5.25a

75. Noncyclic Photophosphorylation
ANIMATION Photosynthesis: Light Reaction: Noncyclic Photophosphorylation
Figure 5.25b

76. Calvin-Benson Cycle
ANIMATION Photosynthesis: Light Independent Reactions
Figure 5.26

77. Photosynthesis Compared
Table 5.6

78. Chemotrophs Use energy from chemicals Chemoheterotroph
Energy is used in anabolism
Glucose
NAD+
ETC
Pyruvic acid
NADH
ADP + P
ATP

79. Chemotrophs Use energy from chemicals
Chemoautotroph, Thiobacillus ferrooxidans
Energy used in the Calvin-Benson cycle to fix CO2
2Fe2+
NAD+
ETC
2Fe3+
NADH
ADP + P
ATP
2 H+

80. Phototrophs Use light energy
Photoautotrophs use energy in the Calvin-Benson cycle to fix CO2
Photoheterotrophs use energy
Chlorophyll
Chlorophyll oxidized
ETC
ADP + P
ATP

81. Requirements of ATP Production
Figure 5.27

82. A Nutritional Classification of Organisms
Figure 5.28

83. A Nutritional Classification of Organisms
Figure 5.28

84. A Nutritional Classification of Organisms
Figure 5.28

85. Metabolic Diversity among Organisms
Nutritional Type
Energy Source
Carbon Source
Example
Photoautotroph
Light
CO2
Oxygenic: Cyanobacteria plants
Anoxygenic: Green, purple bacteria
Photoheterotroph
Organic compounds
Green, purple nonsulfur bacteria
Chemoautotroph
Chemical
Iron-oxidizing bacteria
Chemoheterotroph
Fermentative bacteria
Animals, protozoa, fungi, bacteria.

86. Polysaccharide Biosynthesis
Figure 5.29

87. Lipid Biosynthesis
Figure 5.30

88. Pathways of Amino Acid Biosynthesis
Figure 5.31a

89. Amino Acid Biosynthesis
Figure 5.31b

90. Purine and Pyrimidine Biosynthesis
Figure 5.32

91. The Integration of Metabolism
Amphibolic pathways: Metabolic pathways that have both catabolic and anabolic functions

92. Amphibolic Pathways
Figure 5.33

93. Amphibolic Pathways
Figure 5.33