Question

If you have TAG molecule in adipose cells, how can fatty acids get into mitochondrial matrix? (starting with TAG in adipose cells and ending with fatty acyl-CoA in matrix; draw the flow and explain details).

Answer 1

This is actually part of process of cleaving fatty acids for energy obtaining. Fatty acids are stored in adipose cells as triglycerides, so the adipose cells must first use an enzyme that cleaves one fatty acid chain from a triglyceride, the enzyme is called: trigliceride lipase.

The fatty acids now are free and the adipose cell sends them into the bloodstream, they reach the target cells, but they cannot enter the mitochondria just like that. The activation signal they need to enter there is the Co enzyme A, why? because that is actually needed in order to undergo beta oxidation, which is the process of obatining energy from lipids. So now an enzyme called fatty acylCo-A ligase, this one will add a CoA group to the fatty acid.

Now the fatty acid is bound to a carnitine molecule, without carnitine it cannot enter, the acylCoA-Carnitine molecule enters to the mitochondria matrix, then the carnitine deattaches and the acylCoA is alone again.

The next steps are already part of the beta oxidation, but those are not requested by now.

This is the drawing: