Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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 ...
View Full Document

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.

Ask a homework question - tutors are online