Question

13) What initial chemical transformation takes place on a fatty acid to activate it for catabolism?

a) A fatty acid is cleaved to acyl-CoA and a chain-shortened fatty acid.

b) A fatty acid is cleaved to pyruvate and a chain-shortened fatty acid.

c) A fatty acid is oxidized to a β-hydroxy fatty acid.

d) A fatty acid is converted to its fatty acyl-CoA.

Answer 1

13) The answer is (d) A fatty acid is converted to its fatty acyl-CoA.

Because:

• The fatty acid must be converted to fatty acyl- CoA. The ATP should be spent to covert a fatty acid to fatty acyl-CoA. This is a form which will break down more easily.
• By reacting with CoA fatty acids are activated to form fatty acyl-CoA. This reaction generally occurs in endoplasmic reticulum or the outer mitochondrial membrane.
• The fatty acids are broken down to acetyl-CoA through beta oxidation inside the mitochondria.
• An ATP is required for this reaction which yields AMP and pyrophosphate.