Question

The primary role citric acid cycle is to collect high energy electrons from the oxidation of carbons in the form of NADH and FADH2. If the electron transport chain is inhibited, would you expect the citric acid cycle to be more active or less active? Explain your answer.

Answer 1

Cellular respiration comprises of the following three metabolic which stages which occurs at different sites in the cell:-

• Glycolysis (cytoplasm)
• Citric acid cycle or Kreb cycle (mitochondrial matrix)
• Oxidative phosphorylation (mitochondrial membrane)

The citric acid cycle is a metabolic pathway that occurs in the mitochondrial matrix. This pathway requires mainly eight enzymes. It completely oxidizes acetate into acetyl-CoA and two molecules of carbon dioxide and water. The citric acid cycle occurs in the mitochondrial matrix. The net products of this cycle are two GTP, six NADH, two _, and four . This cycle produces the largest number of molecule. The citric acid cycle is the largest contributor of electrons in the electron transport chain.

The citric acid cycle (CAC) is used to release the energy that is stored by the oxidation of acetyl-CoA that are derived from proteins, carbohydrates, and fats into ATP (adenosine triphosphate) and (carbon dioxide).

The steps of the CAC are a series of chemical (redox, hydration, decarboxylation, and dehydration) reactions. Every turn of the cycle produces:-

• One GTP or ATP
• Three NADH molecules
• One molecule

In the citric acid cycle, half of the steps are oxidation, in which the energy of oxidation is conserved in the form of reduced coenzyme and NADH molecules very efficiently.

The summary of electrons available from the oxidation of one molecule of glucose is given below: -

The citric acid cycle is shown below:-

The electron transport chain consumes NADH and FADH while donating their electron and they are changed into NAD+ and FAD+. If the electron transport chain stops functioning or working, the NADH and FADH that are produced by the citric acid cycle build-up and the of the Kreb cycle rises or increases to the point that it stops.

Hence, the citric acid cycle will be less active if the electron transport chain stops working or inhibits.