Understanding Biological Processes: Collision Theory and Enzymatic Action

1. Figure 2.18

2. Collision Theory • The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide • Activation energy is the amount of energy needed for them to collide ‘hard’ enough to disrupt electronic configurations and produce a chemical reaction • 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

4. The Mechanism of Enzymatic Action Figure 5.4a

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

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

7. Oxidation-Reduction Reactions • Oxidation: Removal of electrons. The general process of electron donation to an electron acceptor is also referred to as oxidation even though the electron acceptor may not be oxygen. • Reduction: Gain of electrons • Redox reaction: An oxidation reaction paired with a reduction reaction

8. Oxidation-Reduction Figure 5.9

9. The Generation of ATP • ATP is generated by the phosphorylation of ADP

10. 3 Ways ATP is Produced in Living Cells • Substrate-Level Phosphorylation. • Occurs during glycolysis (or alternate pathway) during • Fermentation (in Microbes and our • own skeletal muscle cells and brain • Cells) • b. Respiration: Glycolysis and Krebs Cycle • 2. Oxidative Phosphorylation • Occurs during respiratory e- transport chains • (aerobic or anaerobic) • 3. Photophosphorylation. • Occurs during photosynthesis

11. 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. • This is how the process of FERMENTATION produces ATP.

12. 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 • 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

13. 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). This process releases energy used to bond a phosphate to ADP producing ATP. • The ATP produced is used to produce food molecules (sugars-glucose).

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

15. Representative Biological Oxidation Figure 5.10

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

17. 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

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

19. The Krebs Cycle Figure 5.13

20. Chemiosmotic Generation of ATP Figure 5.16

21. Comparing Eukaryotic and Prokaryotic Cellular Location of Catabolic Processes

22. 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.

23. Anaerobic Respiration

24. Fermentation • 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

25. An Overview of Fermentation Figure 5.18a

26. Types of Fermentation Figure 5.19

27. Types of Fermentation Table 5.4

28. Types of Fermentation Table 5.4

29. Catabolism of Organic Food Molecules Figure 5.21

30. Photosynthesis • Conversion of light energy into chemical energy (ATP) and nutrients (glucose) • Overall Summary Reaction? • Compare and Contrast: Oxidative Phosphorylation and Photophosphorylation.

31. Photosynthesis • Oxygenic: • Anoxygenic:

32. Metabolic Diversity among Organisms

33. Amphibolic Pathways Figure 5.33

34. Amphibolic Pathways Figure 5.33