AP BIOLOGY

Detailed explanation-1: -Pyruvate is produced by glycolysis in the cytoplasm, but pyruvate oxidation takes place in the mitochondrial matrix (in eukaryotes). So, before the chemical reactions can begin, pyruvate must enter the mitochondrion, crossing its inner membrane and arriving at the matrix.

Detailed explanation-2: -In aerobic conditions, pyruvate is primarily transported into the mitochondrial matrix and converted to acetyl-coenzyme A (acetyl-CoA) and carbon dioxide by the pyruvate dehydrogenase complex (PDC).

Detailed explanation-3: -Both pyruvate oxidation and the Krebs cycle occur in the mitochondrial matrix, the innermost portion of the mitochondrion.

Detailed explanation-4: -Pyruvate dehydrogenase and carboxylase enzymes are localized to the mitochondrial matrix and, therefore, pyruvate must be transported from the cytosol through both the outer and the inner mitochondrial membranes.

Detailed explanation-5: -Pyruvate is synthesised in the cytosol by the process of glycolysis. For energy synthesis, pyruvate enters the mitochondria by active transport with the help of pyruvate translocase, a transport protein. Pyruvate is utilised in the citric acid cycle to produce acetyl CoA.