Final answer:
Acetyl CoA is transported into the mitochondrial matrix via the Carnitine Shuttle, which involves conversion to acyl-carnitine for membrane crossing and reconversion to acetyl CoA inside the matrix.
Step-by-step explanation:
Acetyl CoA cannot directly cross the inner mitochondrial membrane. Instead, it is transported into the mitochondrial matrix through the carnitine shuttle. This process begins outside the mitochondrial matrix, where fatty acyl-CoA is converted into acyl-carnitine by the enzyme carnitine acyltransferase I. The acyl-carnitine is then transported across the inner membrane by the carnitine-acylcarnitine translocase.
Inside the matrix, carnitine acyltransferase II reconverts acyl-carnitine back into acetyl CoA, which can then enter the Krebs cycle for further energy production. This fatty acyl CoA combines with carnitine to create a fatty acyl carnitine molecule, which helps to transport the fatty acid across the mitochondrial membrane. Once inside the mitochondrial matrix, the fatty acyl carnitine molecule is converted back into fatty acyl CoA and then into acetyl CoA. The newly formed acetyl CoA enters the Krebs cycle and is used to produce ATP.