What is the role of acetyl CoA in cellular respiration?

Acetyl CoA plays a crucial role in cellular respiration as it delivers acetyl groups to the Krebs cycle for energy production.

Acetyl CoA, or acetyl coenzyme A, is a vital molecule involved in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function in cellular respiration is to convey the carbon atoms within the acetyl group to the Krebs cycle (also known as the citric acid cycle or TCA cycle) to be oxidised for energy production.

Cellular respiration is a set of metabolic reactions that take place in cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break down large molecules into smaller ones, releasing energy in the process.

Acetyl CoA is formed during the second stage of cellular respiration, known as pyruvate decarboxylation. During this stage, each pyruvate molecule from glycolysis (the first stage of cellular respiration) is converted into acetyl CoA. This process occurs in the mitochondria, where each pyruvate molecule is decarboxylated (a carbon atom is removed) and then combined with coenzyme A to form acetyl CoA.

The acetyl CoA then enters the Krebs cycle, where it combines with a four-carbon molecule, oxaloacetate, to form a six-carbon molecule, citrate. This is the first step in the Krebs cycle, and it is here that the acetyl group from acetyl CoA is completely oxidised, producing ATP, NADH and FADH2. These molecules are then used in the final stage of cellular respiration, the electron transport chain, to produce a large amount of ATP, which is the main energy currency of the cell.

In summary, acetyl CoA is a key player in cellular respiration, acting as a carrier for acetyl groups to enter the Krebs cycle. Its role is vital for the production of ATP, the energy that powers all cellular activities.