B. aspartate carbamoyl transferase. C. hypoxanthine-guanine phosphoribosyl transferase. D. purine nucleotide phosphorylase. E. xanthine oxidase. D. Tyrosine becomes an essential amino acid E. Need for a phenylalanine-deficient diet for life 16.
Caffeine has a purine ring in which each of three nitrogen atoms bears a methyl group.
E. creatine phosphate. A. Male steroid hormones B. Cholesterol C. Bile acids D. Glucose E. Ketone bodies 18. B. Pyridoxal phosphate C. Tetrahydrofolate D. Vitamin E E. Biotin 21. D. UTP E. TTP 22. B12 E. Inhibiting oxidation of folic acid 23.