7. Cellular Respiration - Cellular Respiration Metabolism -...

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Cellular Respiration Metabolism - Metabolism: the sum of all chemical reactions in an organism - Metabolic reactions often occur in steps o Metabolic (or biochemical pathway) - Two types of metabolic reactions: o Anabolic reactions: build up molecules (synthesis) Consume energy o Catabolic reactions: break down molecules Release energy Metabolism: obtaining energy (figure 7.20) - Glycolysis and cellular respiration o Simple to describe: the reverse of photosynthesis o The biochemical pathway of breaking down simple sugars (glucose) o A series of catabolic reactions o Extract energy to make ATP o Overall reaction: C 6 H 12 O 6 + 6O 2 -> 6CO 2 + 6H 2 0 Glucose as fuel - Need energy to create order - How do we convert food to energy? - The oxidation of glucose is exergonic: o ∆G = -686 kcal/mol - Given this, does glucose blow up in your cabinets or in your digestive tract? Why not? - Activation energy & controlled oxidation (controlled energy release) o Breakage of bonds occur slowly and thus energy is released periodically Stages of glucose oxidation - Takes place in a complex set of 4 stages:
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o I. Glycolysis: splitting of sugar o II. Oxidation of pyruvate o III. Krebs Cycle (aka. TC, Citric Acid Cycle) o IV. Chemiosmosis/Electron Transport Chain - Last three together are called Cellular Respiration o Glycolysis is separate because almost all organisms can do glycolysis and it is done in various areas Mechanisms of ATP synthesis - ATP synthesis is endergonic - Energy from glucose oxidation used in the synthesis of ATP - Mechanisms of ATP synthesis o Substrate level phosphorylation Uses organic phosphorous o Oxidative phosphorylation Uses inorganic phosphorous Adenosine triphosphate Substrate level phosphorylation (Figure 7.4) - Substrate level phosphorylation o Start with an organic molecule that has a phosphate group (PO 4 ) o Transfer that phosphate directly to ADP, making ATP o Occurs during glycolysis and Krebs cycle but not other processes of cellular respiration (directly produces ATP)
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Oxidative phosphorylation - 2) Second mechanism: oxidative phosophorylation o Transfer of a free (inorganic) phosphate (P i ) to ADP to make ATP o Occurs in cellular respiration o Requires intact mitochondria o Requires electron transport chain
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This note was uploaded on 10/24/2011 for the course BIOL 110 taught by Professor Mason during the Fall '07 term at Purdue University-West Lafayette.

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7. Cellular Respiration - Cellular Respiration Metabolism -...

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