Question

Question 1 A-C

Question 2

Question 1: Glycolysis represents only very limited oxidation of glucose into pyruvate, and may be followed up by fermentation involving reduction of pyruvate, not further oxidation. Part A. (4 points) Explain how one molecule of NAD+ plays important roles in both parts of the above paired reactions, specifically mentioning how it is involved in both oxidation and reduction Part B. (4 points) The enzymes involved in the reduction of pyruvate to lactate or ethanol have names such as lactate dehydrogenase and alcohol dehydrogenase. Those names suggest removal of hydrogen from a substrate .which would be oxidation, wouldn't it? Are these enzymes named incorrectly? Why are they named this way? PartC (4 points) Humans most certainly have the alcohol dehydrogenase gene that codes for the enzyme ADH.Our cells make pyruvate from glycolysis, so why don't we end up making ethanol in our body's tissues? Question 2: (4 points) The glucose that is released as a monomer from a large molecule of glycogen (polysaccharide) can bypass the first ATP-dependent step of glycolysis. Why can it do this? Does that mean a glucose freed from glycogen generates 3 ATP instead of normally 2 ATP during glycolysis because you didn't spend one ATP up front?

Answer 1

NAD⁺ plays an important role in both parts of above paired reactions because glycolysis used NAD⁺ to accept electrons as a part of specific reaction. If there is no NAD⁺, this reaction will come to halt. So, all cells used NADH back into NAD⁺ to keep glycolysis going.

In P/O oxygen NAD⁺ is regenerated from NADH by passing it through ET, while as in absence of oxygen, NADH is electron to acceptor molecule and thus regenerates NAD⁺.

Part B:- Lactate dehydrogenase and alcohol dehydrogenase both enzymes are used in fermentation for representation of oxidized co-enzymes NAD⁺.