Which statement is TRUE regarding tyrosine catabolism?

a) The first step in catabolism of tyrosine is reduction to phenylalanine

b) Tyrosine can be considered solely glucogenic.

c) Atoms from tyrosine's sidechain enter the citric acid cycle as fumarate.

d) All of the statements are true.

e) None of the statements is true.

c) atoms from tyrosine's sidechain enter the citric acid cycle as fumarate.

Explanation:

Tyrosine is an aminoacid that can be considered as glucogenic and ketogenic, it catabolims are divided in two ways.

As a glucogenic aminoacid, first it transforms to fumarate then to oxaloacetate to get some glucose at the end of the citric acid cycle.

But in the other hand, also is going to produce acetoacetate and then acetyl CoA to enter into the citric acid cycle.