Question

Acetyl-CoA is formed from………. and coenzyme A

Answer 1

Hint:Acetyl-CoA is one the important biomolecules which is found in excess quantity in cells, it is involved in many of the biochemical reactions within the cell, it’s aim is to provide acetyl group in many of the reactions. In the Krebs cycle it’s function is to deliver acetyl Group to oxaloacetic acid and participates in the formation of citric acid along with one molecule of carbon dioxide.

Complete answer:
 Acetyl-CoA is synthesised in every part of the cell and also found extensively synthesised in mitochondria. When coenzyme A undergoes acetylation using acetate in the cell acetyl-CoA is formed at low glucose levels in the presence of Acetyl-CoA Synthetase this reaction is coupled with hydrolysis of an nucleotide triphosphate that is ATP.

At high glucose levels, acetyl-CoA is produced in the last step of glycolysis, which becomes one of the reactant molecules to begin Krebs cycle as mentioned above in the hint. The precursor of acetyl-CoA in glycolysis is pyruvate. Pyruvate reacts with coenzyme A (CoA-SH) leading to the synthesis of acetyl-CoA coupled to the reduction of NAD molecules by the release of one molecule of carbon dioxide.

Note:Acetyl-CoA is not only seen in glycolysis, they are also formed in oxidation of fatty acids, Formation of acetyl-CoA is the final step in oxidation of fatty acids, this molecule enters TCA cycle and this produces NADH molecules which enter them electron Transport chain layers yield energy molecules at the end of reaction.