Mitochondria generate ATP from fatty acids or pyruvate; the aerobic pathway is slower but yields more ATP, while glycolysis is quicker but yields less ATP.

“So you know the mitochondria can generate ATP from either fatty acids or pyuvate. pyuvate is is is the breakdown is a is a intermediary breakdown product of of glucose via a process called glycolysis. And both of these processes are constantly occurring. Um, it's just the question is what's the balance in which they're occurring? And of course, are these both equal? No, they're not. Right? Each process has a tradeoff. So the trade-off would simply be stated this way. If you are optimizing for efficiency and you don't care as much about the speed with which you can deliver ATP, you want to take that more aerobic pathway, meaning utilizing oxygen and shuttling the breakdown product of fatty acid or glucose um either in the form of pyuvate or acetal coa into the mitochondria uh to use an oxidative pathway to generate lots of ATP per units of carbon that go”