Question

You are being strangled! Why do you die? Include in your answer a description of the need for O2 for each of the following processes and explain the specific consequences of O2 depletion on each.

-glycolysis

-the citric acid cycle

-the electron transport chain

-fermentation

Answer 1

Glycolysis is the process of breakdown of glucose into pyruvic acid. It a common step for aerobic and anaerobic respiration. Therefore if there is no oxygen in the external medium, this process will occur normally and one molecule of glucose will result in the formation of two molecules of pyruvic acid.

Citric acid cycle is the second step for aerobic respiration. In this process, acetyl coenzyme A is broken down into carbon dioxide and water resulting in the formation of NADH, FADH₂ and ATP. This process takes place only in the presence of oxygen. So, if there is no oxygen in the external medium, then these molecules will not be formed. Citric acid cycle produces maximum number of ATP by oxidative phosphorylation. So if this process is not occurring, then enough ATP molecules will not be formed and the cell would die because of lack of ATP.

Electron transport chain is the process in which high energy electron carriers are oxidized to produce ATP. During aerobic respiration, the final electron acceptor is oxygen in electron transport chain which results in the formation of water. So if oxygen is not in the medium than normal ATP formation will occur but water will not be formed.

Fermentation is the process of breakdown of glucose in the deficiency of oxygen. It is an inefficient process because it produces only two molecules of ATP. The main purpose is the regeneration of NAD+ so that it can enter aerobic respiration. This process will not be affected in the absence of oxygen because it occurs when there is no oxygen in the medium.

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