1. QUESTION OF THE DAY…
All E. coli look alike through a microscope; so how can E. coli O157 be differentiated?

2. Catabolic and Anabolic Reactions
Metabolism: The sum of the chemical reactions in an organism
__________: Provides energy and building blocks for anabolism.
__________: Uses energy and building blocks to build large molecules

3. Role of ATP in Coupling Reactions
QUESTION: How is ATP an intermediate between catabolism and anabolism?
Figure 5.1

4. 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

5. 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

6. Energy Requirements of a Chemical Reaction
Figure 5.2

7. 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
Important Coenzymes: NAD+, NADP+, FAD, Coenzyme A
Holoenzyme: Apoenzyme plus cofactor

8. Components of a Holoenzyme
Figure 5.3

9. Enzyme Specificity and Efficiency
The turnover number is generally 1 to 10,000 molecules per second

10. The Mechanism of Enzymatic Action
Figure 5.4b

11. 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

12. Factors Influencing Enzyme Activity
Temperature – Denatures proteins
pH – Denatures proteins
Substrate concentration – Specificity of enzymes
Inhibitors – Prevent binding of substate/enzyme

13. Effect of Temperature on Enzyme Activity
QUESTION: What happens to an enzyme below its optimal temperature?
Figure 5.5a

14. Effect of pH on Enzyme Activity
Figure 5.5b

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

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

17. Enzyme Inhibitors: Competitive Inhibition

18. Enzyme Inhibitors: Noncompetitive Inhibition
Figure 5.7a, c

19. Enzyme Inhibitors: Feedback Inhibition
QUESTION: Why is feedback inhibition noncompetitive inhibition?
Figure 5.8

20. Ribozymes
RNA that cuts and splices RNA

21. Oxidation-Reduction Oxidation: Removal of electrons
Reduction: Gain of electrons
Redox reaction: An oxidation reaction paired with a reduction reaction
Figure 5.9

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

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

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

25. 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

26. 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.
QUESTION: Can you outline the three ways that ATP is generated?

27. Metabolic Pathways of Energy Production

28. Carbohydrate Catabolism
The breakdown of carbohydrates to release energy
Glycolysis
Krebs cycle
Electron transport chain
REVIEW THESE CONCEPTS FROM CELL BIOLOGY!!

29. 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
QUESTION: What is the value of the pentose phosphate and Entner-Doudoroff pathways if they produce only one ATP molecule?

30. Overview of Respiration and Fermentation
Figure 5.11

31. Chemiosmotic Generation of ATP
QUESTION: How do carrier molecules function in the electron transport chain?
Figure 5.16

32. An Overview of Chemiosmosis
Figure 5.15

33. 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.

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

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

36. 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

37. 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

38. 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

39. 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)

40. 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

41. An Overview of Fermentation
ANIMATION Fermentation
Figure 5.18a

42. End-Products of Fermentation
Figure 5.18b

43. 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

44. Types of Fermentation
Compare the energy yield (ATP) of aerobic and anaerobic respiration – which one is more efficient?
Figure 5.19

45. A Fermentation Test
Figure 5.23

46. Types of Fermentation
Table 5.4

47. Lipid Catabolism
Figure 5.20

48. Catabolism of Organic Food Molecules
Figure 5.21

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

50. Protein Catabolism
Decarboxylation
Figure 5.22

51. Protein Catabolism
Desulfurylation
Figure 5.24

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

53. Biochemical Tests Used to identify bacteria.
QUESTION: Could biochemical tests be used to differentiate between Pseudomonas and Escherichia – explain.
Clinical Focus Figure A

54. 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

55. Photosynthesis Oxygenic: Anoxygenic:
QUESTION: How is photosynthesis important to catabolism?

56. Cyclic Photophosphorylation
QUESTION: What is made during the light-dependent reactions?
Figure 5.25a

57. Noncyclic Photophosphorylation
QUESTION: How are oxidative phosphorylation and photophosphorylation similar?
Figure 5.25b

58. Calvin-Benson Cycle
Figure 5.26

59. Photosynthesis Compared
Table 5.6

60. Requirements of ATP Production Phototrophs verses Chemotrophs
Figure 5.27

61. A Nutritional Classification of Organisms
Figure 5.28

62. A Nutritional Classification of Organisms
Figure 5.28

63. A Nutritional Classification of Organisms
Figure 5.28

64. 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.
QUESTION: Almost all medically important microbes belong to which of the four aforementioned groups?

65. Polysaccharide Biosynthesis
Figure 5.29

66. Lipid Biosynthesis
Figure 5.30

67. Pathways of Amino Acid Biosynthesis
Figure 5.31a

68. Amino Acid Biosynthesis
Figure 5.31b

69. Purine and Pyrimidine Biosynthesis
Figure 5.32

70. The Integration of Metabolism
Amphibolic pathways: Metabolic pathways that have both catabolic and anabolic functions
Glycolysis Kreb’s Cycle