text: The second step of fatty acid degradation is beta oxidation. Beta oxidation occurs in mitochondria.  After formation in the cytosol, acyl-CoA is transported into the mitochondria, the locus of beta oxidation.  Transport of acyl-CoA into the mitochondria requires carnitine palmitoyltransferase 1 (CPT1), which converts acyl-CoA into acylcarnitine, which gets transported into the mitochondrial matrix.  Once in the matrix, acylcarnitine is converted back to acyl-CoA by CPT2.  Beta oxidation may begin now that Acyl-CoA is in the mitochondria.  
  Beta oxidation of acyl-CoA occurs in four steps.
  1.      Acyl-CoA dehydrogenase catalyzes dehydrogenation of the acyl-CoA, creating a double bond between the alpha and beta carbons.  FAD is the hydrogen acceptor, yielding FADH2.
  2.      Enoyl-CoA hydrase catalyzes the addition of water across the newly formed double bond to make an alcohol.
  3.      3-hydroxyacyl-CoA dehydrogenase oxidizes the alcohol group to a ketone. NADH is produced from NAD+.
  4.      Thiolase cleaves between the alpha carbon and ketone to release one molecule of Acetyl-CoA and the Acyl-CoA which is now 2 carbons shorter.
  This four step process repeats until acyl-CoA has removed all carbons from the chain, leaving only Acetyl-CoA. During one cycle of beta oxidation, Acyl-CoA creates one molecule of Acetyl-CoA, FADH2, and NADH.  Acetyl-CoA is then used in the citric acid cycle while FADH2 and NADH are sent to the electron transport chain. These intermediates all end up providing energy for the body as they are ultimately converted to ATP.
  Beta oxidation, as well as alpha-oxidation, also occurs in the peroxisome. The peroxisome handles beta oxidation of fatty acids that have more than 20 carbons in their chain because the peroxisome contains very-long-chain Acyl-CoA synthetases.  These enzymes are better equipped to oxidize Acyl-CoA with long chains that the mitochondria cannot handle.