BASES The bases are nitrogen-containing ring compounds, either pyrimidines or purines. CCCHCNHNHOOCCHCNHNONH2H3CCCHCNHNHOOHCHCUCTuracilcytosinethymineN N 1 2 3 4 5 6 N N 1 2 3 4 5 6N N 7 8 9 O N N H C C C C N NH NH2 HC N N H C C C CH N N HC NH2 adenine guanine A G PYRIMIDINE PURINE 100 PaNel 2–6: a Survey of the Nucleotides
NUCLEOTIDESA nucleotide consists of a nitrogen-containing base, a fve-carbon sugar, and one or more phosphate groups. HHONH2OCH2OHOHBASE PHOSPHATE SUGAR Nucleotides are the subunits of the nucleic acids.The phosphate makes a nucleotide negatively charged.
PHOSPHATES The phosphates are normally joined to the C5 hydroxyl of the ribose or deoxyribose sugar (designated 5'). Mono-, di-, and triphosphates are common.
The base is linked to the same carbon (C1) used in sugar–sugar bonds.
SUGARS Each numbered carbon on the sugar of a nucleotide is followed by a prime mark; therefore, one speaks of the “5-prime carbon,” etc. OH OH O H H HOCH2 OH H H OH H O H H HOCH2 OH H H PENTOSE a fve-carbon sugar O 4’ 3’ 2’ 1’ C 5’ two kinds are used ˜-D-ribose used in ribonucleic acid ˜-D-2-deoxyribose used in deoxyribonucleic acid