Chapter 2 energetics

1. Metabolism : The sum of the chemical reactions in an organism A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell Metabolic pathways are determined by enzymes

2. Catabolic and Anabolic Reactions Catabolism : Provides energy and building blocks for anabolism. (Break down) Anabolism : Uses energy and building blocks to build large molecules. (Synthesis)

3. Metabolism: the sum of Catabolism and Anabolism Oxidation: the loss or removal of electrons Reduction: the gain of electrons

4. Figure 5.1 Role of ATP in Coupling Reactions

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

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

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

8. Substrate-Level Phosphorylation Energy from the transfer of a high-energy PO 4 – to ADP generates ATP

9. 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

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

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

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

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

14. The Reactions of Glycolysis

15. The Krebs Cycle Oxidation of acetyl CoA produces NADH and FADH 2

16. Figure 5.13 The Krebs Cycle

17. The Reactions of the Krebs Cycle

18. 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

19. Figure 5.11 Overview of Respiration and Fermentation

20. Figure 5.16 Chemiosmotic Generation of ATP

21. Figure 5.15 An Overview of Chemiosmosis

22. A Summary of Respiration Aerobic respiration : The final electron acceptor in the electron transport chain is molecular oxygen (O 2 ). Anaerobic respiration : The final electron acceptor in the electron transport chain is not O 2 . Yields less energy than aerobic respiration because only part of the Krebs cycles operates under anaerobic conditions.

23. Figure 5.16 Respiration

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

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

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

27. Fermentation One process by which pyruvate is subsequently metabolized in the absence of oxygen The result of the need to recycle the limited amount of NAD by passing the electrons of reduced NAD to other molecules Homolactic acid fermentation : pyruvate is converted directly to lactic acid , using electrons from reduced NAD Alcoholic fermentation: carbon dioxide is released from pyruvate to form acetaldehyde , which is reduced to ethanol

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

29. 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

30. Figure 5.18a An Overview of Fermentation

31. Figure 5.19 Types of Fermentation

32. Figure 5.27 Requirements of ATP Production

33. Figure 5.28 A Nutritional Classification of Organisms

34. Figure 5.28 A Nutritional Classification of Organisms

35. Figure 5.28 A Nutritional Classification of Organisms

36. Nutritional Type Energy Source Carbon Source Example Photoau totroph Light CO 2 Oxygenic : Cyanobacteria plants Anoxygenic : Green, purple bacteria Photohete rotroph Light Organic compounds Green, purple nonsulfur bacteria Chemoau totroph Chemical CO 2 Iron-oxidizing bacteria Chemohetero troph Chemical Organic compounds Fermentative bacteria Animals, protozoa, fungi, bacteria. Metabolic Diversity among Organisms