What is the role of acetyl-CoA carboxylase in metabolism and what cofactor is required?

Study for the Biochemistry Module 6 Exam. Study with flashcards and multiple choice questions; each question includes hints and explanations. Gear up to ace your test!

Acetyl-CoA carboxylase carries out the first, committed step of fatty acid synthesis by converting acetyl-CoA into malonyl-CoA. This carboxylation reaction adds a one-carbon group to acetyl-CoA and requires ATP and bicarbonate, with biotin acting as the essential carrier of the carboxyl group. Biotin is attached to a lysine on the biotin carboxyl carrier protein, gets carboxylated, and then transfers the carboxyl group to acetyl-CoA to form malonyl-CoA, which then feeds the fatty acid synthase cycle to extend the growing fatty acid chain. This is why the correct answer emphasizes the conversion of acetyl-CoA to malonyl-CoA in fatty acid synthesis and that biotin is the required cofactor. Other options describe reactions in different pathways (TCA cycle or glycolysis) or incorrect substrates and cofactors, which don’t match ACC’s role.