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Quiz 15 key - As a result the liver synthesizes ketone...

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Biochemistry 309, Winter 2010 20 points Quiz #15 NAME:_______________________________ TA:__________________ 1. Which hormone signals a high concentration of glucose in the body? (1 point) Insulin Which hormone signals low glucose in the body? (1 point) Epinephrin and glucagon 3. Changing the oxidation state of carbon is common to many pathways and generally uses the same strategy. Draw the structures of plausible intermediates for the conversion between the following molecules. Also name each reaction and provide any plausible cofactors. (8 points) 4. Under starvation conditions, does the liver oxidize or synthesize glucose? How does this affect the utilization of fatty acids? (4 points) The liver synthesizes glucose from oxaloacetate for export to the muscles and the brain. This depletes the OAA and intermediates from the TCA cycle. This limits the amount of acetyl-CoA that can be oxidized to CO2.
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Unformatted text preview: As a result, the liver synthesizes ketone bodies from the aceyl-CoA for export to the brain and tissues. 5. For a fatty acid having 17 carbons, what are the products of oxidation and how many carbons can be converted into glucose through gluconeogenesis? Explain. (4 points) The oxidation of a 17 carbon fatty acid leads to the production of 7 acetyl-CoAs, and one propionyl-CoA. Acetyl-CoA cannot be used in gluconeogenesis. Propionyl-CoA can be converted to succinyl-CoA and oxaloacetate, which can enter gluconeogenesis. Therefore, 3 carbons of the 17 can be converted into glucose. 6. If a cell has high concentrations of malonyl-CoA, how would this affect fatty acid synthesis vs oxidation? (2 points) Malonyl-CoA inhibits carnitine acyltransferase, which catalyzes the committed step in fatty acid oxidation. This mean that the cell would synthesize fatty acids instead of oxidizing them....
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