4.  From normal turnover of cellular nucleic acids  Obtained from the diet  Reutilization of adenine, hypoxanthine, and guanine  Two enzymes: 1. Adenine phosphoribosyltransferase 2. Hypoxanthine-guanine phosphoribosyltransferase

7. Hypoxanthine Xanthine Xanthine dehydrogenase Allopurinol

9. Build up of hypoxanthine and guanine Degradation of hypoxanthine and guanine results in increased uric acid Absence of Hypoxanthine-guanine phosphoribosyltransferase. Excess uric acid in urine often results in orange crystals in the diaper of affected children Severe mental retardation Self-mutilation Involuntary movements Gout Lesch-Nyhan Syndrome

14. Very Important!

16. Guanine-Cytosine Adenine-Thymine DNA Base Pairing

17.  %A = %T and %G = %C  In DNA, 1:1 ratio between purines and pyrimidines Organism%A%G%C%TA/TG/C%GC%AT φX17424.023.321.531.20.771.0844.855.2 Maize26.822.823.227.20.990.9846.154.0 Octopus33.217.6 31.61.051.0035.264.8 Chicken28.022.021.628.40.991.0243.756.4 Rat28.621.420.528.41.011.0042.957.0 Human29.320.720.030.00.981.0440.759.3 Grasshopper29.320.520.729.31.000.9941.258.6 Sea Urchin32.817.717.332.11.02 35.064.9 Wheat27.322.722.827.11.011.0045.554.4 Yeast31.318.717.132.90.951.0935.864.4 E. Coli24.726.025.723.61.051.0151.748.3

18.  Purines: Uric acid  Reutilization of adenine, hypoxanthine and guanine  End product: Urate (a.k.a.: Uric Acid )  Altered metabolism: Gout  Pyrimidines: Citric acid intermediates  Acetyl-CoA derived from Cytosine and Uracil degradation; Propionyl-CoA (Succinoyl-CoA) from Thymine degradation  Ammonia and CO 2  Ring undergoes complete degradation