SI session Oct. 16 Ch. 9 and 10 answers

SI session Oct. 16 Ch. 9 and 10 answers - Kaiser Imam...

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Kaiser Imam October 16, 2007 BIOL 215 SI Session Chapters 9 and 10 Chapter 9: Glycolysis and Fermentation 1. What is the difference in Δ G ° between the combustion of a marshmallow over a fire and the biological oxidation of that marshmallow by respiration? There is no difference. The Δ G ° value is the same for both processes and it is unaffected by the route taken to release the energy. Thus, burning the marshmallow will release the same amount of energy as biological oxidation. However, in combustion much of the free energy is lost as heat. Biological oxidations can more efficiently channel the energy produced from oxidation to do other work in the cell. 2. What is the difference between aerobic respiration and anaerobic respiration? Aerobic respiration uses O 2 as the final electron acceptor while anaerobic respiration uses electron acceptors other than oxygen such as NO 3 - , SO 4 - , etc. 3. Distinguish between the following types of organisms. a) Obligate aerobes Require oxygen to survive. b) Obligate anaerobes Cannot use oxygen as an electron acceptor under any conditions. Oxygen can be toxic to these organisms. c) Facultative anaerobes Can function in either aerobic or anaerobic conditions. Most use oxygen for respiration if its available and use fermentation if oxygen is limiting or absent. 4. What is substrate-level phosphorylation? Substrate-level phosphorylation is the formation of ATP by the direct transfer of a high- energy phosphate group derived from a phosphorylated substrate to a molecule of ADP. This process occurs at a few key steps in glycolysis. 5. List the 3 phases of glycolysis and describe key events within each. 1) Gly-1 → Gly-5 ____ Preparation and Cleavage ______________ Begins with a molecule of glucose 2 ATP molecules are hydrolyzed to phosphorylate glucose twice to form fructose-1,6- bisphosphate 1
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ATP not only provides the phosphate groups but also makes the phosphorylation highly exergonic so that the reaction is irreversible in the direction of glucose phosphorylation Division of fructose-1,6-bisphosphate into two 3-carbon sugars: a molecule each of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G-3-P) Triose phosphate isomerase converts DHAP to G-3-P 2) Gly-6 → Gly-7 ____ Oxidation and ATP Generation _________ Reduction of 2 molecules of NAD + to form 2NADH + 2H + Formation of 2 molecules of ATP by substrate-level phosphorylation resulting in the formation of 2 molecules of 3-phosphoglycerate 3) Gly-8 → Gly-10 ____ Pyruvate Formation and ATP Generation _ Removal of 2 molecules of water to form 2 phosphoenolpyruvate (PEP) Substrate-level phosphorylation of PEP to form 2 molecules of ATP and 2 pyruvate 6. Write a general reaction equation for the glycolysis process. Glucose + 2 ADP + 2 P
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SI session Oct. 16 Ch. 9 and 10 answers - Kaiser Imam...

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