We use a single ATP molecule and we also use a coenzyme A to basically transform a fatty acid into acyl coenzyme A. So an acyl coenzyme A is essentially a fatty acid that is attached to a coenzyme A. And this basically activates our fatty acid. And now we can transport the fatty acid into the mitochondrial matrix using a special transport mechanism that involves a molecule known as carnitine. So carnitine is the molecule that helps transport our acyl coenzyme A that contains the fatty acid into the mitochondrial matrix. Now, once the fatty acid, specifically once inside the acyl coenzyme A is inside the mitochondrial matrix, the ACL coenzyme A molecule is shortened by two carbons via a series of four reactions that are known as beta oxidation because the cutting takes place on the beta carbon.