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Unformatted text preview: 1 April 8, April 8, 2008 2008 Biology 113, Lecture 5 Biology 113, Lecture 5 • Catabolic pathways and production of ATP • Redox reactions • Glycolysis (splitting of sugar) Concepts : 9.1 and 9.2 Part 1 - Outline Cellular Respiration: Harvesting Chemical Energy (Chapter 9) Catabolic processes: • Cellular respiration (requires O 2 ) • most prevalent and efficient process • Fermentation (occurs in the absence of O 2 ) • partial degradation process Catabolic pathways yield Catabolic pathways yield energy by oxidizing organic fuels. energy by oxidizing organic fuels. Amino acids Sugars Glycerol Fat y acids Glycolysis Glucose Glyceraldehyde-3- P Pyruvate Acetyl CoA NH 3 Citric acid cycle Oxidative phosphorylation Fats Proteins Carbohydrates Catabolism of various molecules from food Catabolism of various molecules from food feeds into feeds into glycolysis glycolysis and the citric acid cycle. and the citric acid cycle. Figure 9.19 Carbohydrates (sugars) provide “quick” energy by “feeding both Processes. Fats are high in energy because of the high number of electrons available from the oxidation of the large number of –CH 2 – groups. Thus, fats are a great way to “store energy” for later use. Proteins are not a good source of energy by these pathways (starvation). Glucose oxidation: glucose + 6 O 2 6 CO 2 + 6 H 2 O + energy Energy is obtained by the cell by respiration Energy is obtained by the cell by respiration- the process of oxidizing glucose to CO the process of oxidizing glucose to CO 2 becomes oxidized becomes reduced (electrons) (loss of electrons) (gain of electrons) becomes reduced C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy becomes oxidized Production of energy by burning or respiration Production of energy by burning or respiration ATP Respiration: Gradual release of energy More More “useable useable ” energy can be extracted energy can be extracted from each step in a more from each step in a more “orderly orderly ” manner. manner. The “extracted” energy is stored in two ways: 1. As ATP (through substrate-level phosphorylation) 2. As “electropotential energy” (storage of electrons) 2 The coenzymes NAD The coenzymes NAD + and FAD and FAD “store store ” electrons electrons chemically with little loss in energy chemically with little loss in energy for transport and later use for transport and later use Oxidized Reduced NAD + NADH FAD FADH 2 Mitochondria ATP Figure 9.4 “Controlled” release of energy by oxidation reactions in biological systems Fig. 9.5 Use of electron...
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This note was uploaded on 04/29/2008 for the course BIO 113 taught by Professor Swenson during the Spring '08 term at Ohio State.
- Spring '08
- Cellular Respiration