The Mechanism of Enzymatic Action

2. The Mechanism of Enzymatic Action Figure 5.4a

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

4. Enzyme Inhibitors: Competitive Inhibition Example-Sulfa drugs (sulfonamides) Discovered in the 1930s

5. Oxidation-Reduction Figure 5.9

6. Representative Biological Oxidation Figure 5.10

7. The Generation of ATP • ATP is generated by the phosphorylation of ADP • Substrate-level Phosphorylation • Oxidative Phosphorylation • Photophosphorylation

8. Substrate-Level Phosphorylation • A chemical reaction where a phosphate group is transferred from one molecule to ADP. This requires a specific enzyme that can transfer the phosphate from this specific molecule to ADP. • ATP is produced this way during • FERMENTATION • Glycolysis (or alternative pathways) • Krebs cycle

9. Oxidative Phosphorylation • Energy released from transfer of electrons (oxidation) from one compound to another (reduction) is used to generate ATP in the electron transport chain • An electron transport chain(ETC) couples a chemical reaction between an electron donor (such as NADH) and an electron acceptor (such as O2) to the transfer of H+ ions across a membrane, through a set of mediating biochemical reactions. http://en.wikipedia.org/wiki/Electron_transport_chain

10. Photophosphorylation • Light causes chlorophyll to give up electrons. The electrons go through a process similar to what happens during respiration (an electron transport chain and chemiosmosis occur). This process releases energy used to bond a phosphate to ADP producing ATP. • The ATP produced is used to produce food molecules (sugars-glucose).

11. Glycolysis • The oxidation of glucose to pyruvic acid produces ATP (Substrate level phosphorylation)and NADH 2 Stages: See next 2 slides Figure 5.11

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

13. ATP Creating Stage of Glycolysis • 2 glucose-3-phosphate oxidized to 2 pyruvic acid • 4 ATP produced • Substrate-level phosphorylation • 2 NADH produced Figure 5.12, steps 6–10

14. Preparatory Step Intermediate between Glycolysis and Krebs Cycle • Pyruvic acid (from glycolysis) is oxidized and decarboyxlated Figure 5.13

15. The Krebs Cycle Figure 5.13

16. Chemiosmotic Generation of ATP Figure 5.16

17. Comparing Eukaryotic and Prokaryotic Cellular Location of Catabolic Processes

18. Aerobic and Anaerobic 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.

19. Anaerobic Respiration

20. Fermentation • FERMENTATION Scientific definition: • Releases energy from oxidation of organic molecules • Does not use oxygen • Does not use the Krebs cycle or ETC • Uses an organic molecule (pyruvic acid) as the final electron acceptor to form ‘end-products’ (acids and alcohols) • 2 ATPs netted

21. An Overview of Fermentation Figure 5.18a

22. Types of Fermentation Figure 5.19

23. Types of Fermentation Table 5.4

24. Types of Fermentation Table 5.4

25. Catabolism of Organic Food Molecules Figure 5.21

26. Photosynthesis • Conversion of light energy into chemical energy (ATP) which is used to synthsize nutrients (glucose) • Overall Summary Reaction? • Compare and Contrast: Oxidative Phosphorylation and Photophosphorylation.

27. Photosynthesis • Oxygenic: • Anoxygenic:

28. Metabolic Diversity among Organisms

29. Amphibolic Pathways Figure 5.33

30. Amphibolic Pathways Figure 5.33