Question

12. Explain how citric acid cycle Is connected to the electron transport chain. what is the role of molecular oxygen (O2) for citric acid cycle? why will blocking the electron transport chain halt the citric acid cycle?

Answer 1

Citric acid cycle is the process which leads to the formation of various fatty acid intermediates, GTP and high energy electron carriers NADH and FADH₂. It is a crucial step in aerobic respiration. This step generates the maximum number of ATP out of all other steps of cellular respiration.

In this process every intermediate is oxidized to the other intermediate. This happens by loss of electrons from these intermediates which are ultimately accepted by high energy electron Carriers. Therefore if the production of oxygen is blocked, then citric acid cycle will not take place. Instead fermentation or anaerobic respiration will take over.

The high energy electron Carriers produced in citric acid cycle are the sources of electrons in electron transport chain. They donate their electron to the complexes located in the inner mitochondrial membrane. This leads to the start of electron transport chain where one Complex donate the electrons to the other Complex. Ultimately the electrons accepted by oxygen which is reduced to form water. Water is the byproduct of cellular respiration.

When electrons are transferred from one electron carrier to the other, protons are also pumped from mitochondrial Matrix to intermembrane space. This leads to the generation of Differential concentration of protons. Protons are then pumped back into the mitochondrial matrix by ATP synthase enzyme This leads to spinning of this enzyme and thereby phosphorylating ADP to ATP.

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