A major role of vitamin B-12 in cellular metabolism is
A. in transamination reactions, allowing the synthesis of nonessential amino acids.
B. transfer of a methyl group to the pyrimidine uracil, forming the pyrimidine thymine.
C. transfer of a methyl group to the amino acid homocysteine, forming the amino acid methionine.
D. as an electron acceptor, allowing function of the electron transport chain.
Answer: C
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