The conversion of pyruvate to acetyl-CoA. A. requires the addition of CO2 B. occurs in the mitochondria of the cell and is irreversible. C. occurs in he nucleus of the cell. D. is needed for red blood cell production. Solution The conversion of pyruate to acetyl COA (B) occurs in the mitochondria of the cell and is irriversible. The process is carriedout with the help of an enzyme pyruate dehydrogenase, which is located in mitochondrial matrix. During the conversion process each pyruate molecule loses one carbon atom with the release of CO2..