CTools020411lecture12

CTools020411lecture12 - Lecture 12: Friday, February 4,...

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Unformatted text preview: Lecture 12: Friday, February 4, 2011 Biology 172 Todays Outline Announcements Review Glycolysis Fermentation Formation of Acetyl CoA Cellular Respiration- Citric Acid Cycle- Electron Transport Chain- Oxidative Phosphorylation- ATP Synthase- ATP Yield- Catabolism of Other Fuels Discussion Next Week: Herbicides Quiz on Lectures 11-13 Overview of Cellular Metabolism C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy Overall Equation: the oxidation of glucose (and other fuel molecules) to generate useful energy Three Pathways of Energy Formation: Citric Acid Cycle Energy input and output of glycolysis G = -140 kcal/mol Todays Outline Cellular Metabolism- Overview- Glycolysis- Fermentation Pyruvate is a key juncture in catabolism The end product of glycolysis ( pyruvate ) feeds into both fermentation and cellular respiration Organisms that can use both fermentation and respiration are facultative anaerobes ( e.g. yeast and many bacteria) Muscle cells in animals function this way Figure 9.24 Cellular Respiration and Fermentation Are Alternative Pathways for Producing Energy Cellular respiration If electron acceptor (such as oxygen) is present If electron acceptor (such as oxygen) is NOT present Fermentation Anaerobic reactions Provide NAD+ to re-charge glycolysis Lower energy yield - only 2 ATP per glucose Fermentation by-product Intermediate accepts electrons from NADH Fermentation Lactic acid fermentation occurs in humans. 2 Pyruvate 2 Lactate No intermediate; pyruvate accepts electrons from NADH Alcohol fermentation occurs in yeast. 2 Pyruvate 2 Acetylaldehyde 2 Ethanol Figure 9.25 Catabolic pathways break down complex organic molecules and release the stored energy Cellular respiration (aerobic) Oxygen is consumed as a reactant along with organic fuel Occurs in mitochondria (eukaryotes) Exergonic reaction: energy used to generate ATP (& wasted as heat) Fermentation (anaerobic) Partial degradation of organic compounds in the absence of oxygen Not as efficient as cellular respiration Pyruvate is a key juncture in catabolism The end product of glycolysis ( pyruvate ) feeds into both fermentation and cellular respiration Without oxygen pyruvate is an electron acceptor for fermentation, which oxidizes NADH back to NAD+ With oxygen pyruvate enters mitochondria and its chemical energy is used in cellular respiration to generate ATP Pyruvate enters the mitochondrion Pyruvate is converted to acetyl CoA with the release of CO 2 Coenzyme A is derived from a B vitamin One molecule of NADH is generated for each pyruvate Important Coenzymes NAD+ FAD CoA Q An overview of cellular respiration Electrons carried via NADH Glycolsis Glucose Pyruvate ATP Substrate-level phosphorylation Electrons carried via NADH and FADH 2 Citric acid cycle Oxidative phosphorylation: electron transport and chemiosmosis ATP ATP Substrate-level phosphorylation Oxidative phosphorylation Mitochondrion Glycolysis is regulated in response to the...
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CTools020411lecture12 - Lecture 12: Friday, February 4,...

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