So once again, under aerobic conditions, NADH molecules produced in glycolysis must be transported into the mitochondria. Why? Well, because the cell must use the NADH molecules to not only produce ATP molecules, but to also regenerate the NAD plus Co enzyme that is needed for glycolysis to actually continue taking place. Now, there are actually different ways by which the NADH molecules can actually get into the mitochondria. And in this lecture, I'd like to focus on a specific type of membrane transport system known as the glycerol three phosphate shuttle. And this is the shuttle that is used predominantly by skeletal muscle cells of our body.