7. (3 pts) Chronic alcoholism can lead many metabolic consequences. The metaboli

Question

7. (3 pts) Chronic alcoholism can lead many metabolic consequences. The metabolism of ethanol in the liver is shown below. Excessive consumption of alcohol produces an excess of NADII resulting in 1) decrcascd blood pH duc to lactate build-up, 2) formation of a fatty liver, and 3) thc incrcascd formation of acetyl-CoA from acetate and CoA triggering a further decreased blood pH by another mechanism. NAD NADH +H NAD NADH+H Acetyl Athanolj Aleoholi -Acetaldhy Acotaidhyde AcetateACoAT -Acetaldehyde (ethanol) Alcohol Acetaldehyde dehydrogenase dehydrogenase COA O2007 Themaon Hiher Education a. Explain the biochemical causes of the first two and the role played by NADIH. b. Why does an increase in acetyl-CoA (3) lead to a further decrease in blood pII?

Explanation / Answer

a. Ethanol cannot be excreted. It has to be metabolized in liver. Th metabolism of ethanol in liver consists of two steps-

Alcohol is converted into acetaldehyde in presence of alcohol dehydrogenase. Then acetaldehyde converts into acetate in presence of aldehyde dehydrogenase. Both the reactions forms NADH, as a result NADH increases. This increased NADH inhibits the process of gluconeogenesis and thus preventing the conversion of lactate into pyruvate. Instead, NADH promotes formation of lactate, decreased glucose level.

b. The increase in acetyl co-enzyme A causes the NADPH to convert into NADP+, which generates free radicals as this reaction uses oxygen. Accumulation of ketone bodies causes acidosis which was already started due to accumulation of lactate. Thus decrease in pH.

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