Release of amino acid nitrogen and NH4+ is an important step in generating precursors for the urea cycle. Which statement best describes this release of amino acid nitrogen as NH4+ from amino acids?
A.
NH4+ freely diffuses across membranes.
B.
Glutamate deamination by oxidation is readily reversible.
C.
Serine deamination to pyruvate is readily reversible.
D.
Glutamine deamination to glutamate is readily reversible.
E.
NH3 cannot freely diffuse across membranes.