Chapter 9 CELLULAR RESPIRATION AND FERMENTATION

Chapter 9 CELLULAR - Chapter 9 CELLULAR RESPIRATION AND FERMENTATION Chapter 9 CELLULAR RESPIRATION AND FERMENTATION From Snickers to

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Unformatted text preview: Chapter 9 CELLULAR RESPIRATION AND FERMENTATION Chapter 9 CELLULAR RESPIRATION AND FERMENTATION From Snickers to ATP *Review *ATP *Cellular Respiration *Glycolysis *Pyruvate oxidation *Krebs cycle *Electron Transport chain *Fermentation Summary Review *All of our energy comes from? *This energy is the form of? *Plants convert this energy to? *The energy is potential (stored) energy stored in? *The energy is released by? *Most living organisms require energy in the form of? How Do Cells Make ATP? *Oxidation of sugars, primarily glucose. *Key chemical reactions = REDOX reactions, transfer of electrons and H+ from one substance to another. *Energy is harvested from electrons and used to produce ATP. *ATP is stored in small quantities in cells but is primarily produced on demand by cellular respiration. Cellular Respiration *ATP production: ADP + P → ATP; 2 types ATP *Substrate level phosphorylation *Oxidative phosphorylation *2 types of Cellular Respiration * Aerobic ­ oxygen is used as the final electron acceptor. 1 * Anaerobic – final electron acceptor is an inorganic molecule; some bacteria and archaea. * Fermentation – is also an anaerobic process. 2 Cellular Respiration Cellular Respiration *Summary of aerobic respiration using glucose: C6H12O6 (glucose) + 6O2 → 6CO2 + 6H2O + energy (ATP) 6CO *4 Steps, fig 9.8: Glycolysis *In the cytosol, 10 reactions, 3 stages, fig 9.13 * Glucose (6 C) is primed, using 2 ATP’s, and converted to fructose 1,6 – bisphosphate. *Fructose is split into two 3­C molecules, glyceraldehyde 3­phosphate (G3P) * Energy extraction: electrons and H+ transferred to 2NAD+ and 4 ATPs produced. Final product – 2 pyruvate molecules (3 C). *Summary: Glucose + 2 NAD+ + 4ADP → 2 pyruvate + 2 NADH + 4ATP. *Note: each G3P is oxidized to produce 1 NADH and 2 ATP by substrate level phosphoylation. *2 ATP are used to pay back 2 used at the beginning. * Net Production: Glucose + 2 NAD+ + 4ADP → 2 pyruvate + 2 NADH + **2ATP. Regulating Metabolic Pathways by Feedback Inhibition Pyruvate Oxidation *Takes place in the outer membrane of the mitochondria, fig 9.16 and 9.17. *Each pyruvate (3 C) is oxidized to an acetyl group (2 C). *Each acetyl group is combined with Coenzyme A (CoA) and feeds into the Kreb’s Cycle. *Summary: 2 Pyruvate + 2 CoA + 2 NAD+ → 2CO2 + 2acetyl CoA + 2NADH Krebs Cycle *Takes place in the matrix of the mitochondria, 9 reactions, 2 stages, fig 9.19. * Priming: *Each acetyl CoA (2 C) combines with oxaloacetate (4 C) in Kreb’s cycle to form citrate (6 C). *CoA removed and recycled. 3 * Energy Extraction: *Oxidation reactions transfer electrons and H+ to NAD+ and FADH. Each acetyl group that enters produces 3 NADH and 2 FADH2. *ATP produced by substrate level phosphorylation. Each acetyl group produces 2 ATP. *Summary: *2 acetyl CoA + 2 oxaloacetate + 6NAD+ + 2FADH + 2ADP → *4CO2 + 6NADH + 2FADH2 + **2 ATP + 2 oxaloacetate (remains in Kreb’s Cycle). *Regulation, fig 9.20. The Krebs Cycle Is Regulated by Feedback Inhibition Summary So Far Electron Transport and Oxidative Phosphorylation *So far we have 4ATP and a bunch of electrons (energy) and H+ carried by NADH and FADH2. *NADH and FADH2 transfer electrons to the transport chain (ETC) on the cristae of the mitochondria, fig 9.24. *The ETC “harvests” the energy from the electrons as they pass down the chain. *The energy harvested from the electrons is used to “pump” H+ from the matrix to the intermembrane space of the mitochondria (energy is stored in the H+). *This produces a concentration gradient for H+. *H+ reenter the matrix through the enzyme, ATP synthase. *ATP synthase recovers the energy and produces ATP via oxidative phosphorylation. *Using the H+ gradient to produce ATP is called chemiosmosis. *H+ transferred to O2 to produce H2O. *Summary: 10 NADH + 2 FADH2 + 3O2 → **26 ATP + 6H2O. Add the 2 from glycolysis and 2 from the Kreb’s cycle brings the total to 30 ATPs produced 30 from every glucose molecule. Fermentation Fermentation 4 *Fate of pyruvate in the absence of oxygen. *Allows for ATP production on a small scale by recycling NAD+ for glycolysis. *2 types: *Lactic acid fermentation: *Ethanol fermentation: Cellular Respiration and Other Metabolic Pathways * Metabolism = all of the chemical reactions in an organism * Catabolism = * Anabolism = Cellular Respiration and Other Metabolic Pathways *In the absence of available glucose, fats and proteins can feed into glycolysis and the Kreb’s Cycle, fig 9.29. *Products of glycolysis and the Kreb’s cycle can be used to produce RNA/DNA, proteins and fats, fig 9.30. 5 ...
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This note was uploaded on 09/08/2011 for the course BIOL 1403 taught by Professor Dini during the Fall '09 term at Texas Tech.

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