------------------
21. When proteins need to be used in aerobic respiration (only in cases of severe starvation),
a) the proteins are broken down first into individual amino acids.
b) each amino acid has the amino group removed (deamination). The amino group eventually becomes part of urine.
c) The remaining 2-carbon portions of each amino acid are converted to Acetyl-CoA.
d) this Acetyl-CoA can immediately join the Krebs cycle.
------------------