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Unformatted text preview: Chapter 9 CELLULAR RESPIRATION AND FERMENTATION
Chapter 9 CELLULAR RESPIRATION AND FERMENTATION
From Snickers to ATP *Review
*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.
*ATP production: ADP + P → ATP; 2 types
*Substrate level 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
*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
from every glucose molecule.
Fermentation 4 *Fate of pyruvate in the absence of oxygen.
*Allows for ATP production on a small scale by recycling NAD+ for glycolysis.
*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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