2007-02-26 23:32:24 · 1 answers · asked by amazing_sweet_angel 1 in Science & Mathematics ➔ Chemistry
Cytosine and thymine (DNA) and uracil (RNA) are pyrimidine bases. They consist of a single 6-membered heterocyclic aromatic ring (cytosine has an NH2 group bound to C4 and a keto group =O bound to C2; uracil has 2 keto groups bound to C4 and C2; thymine is similar to uracil but with an additonal methyl group bound to C5). Adenine and guanine are purine bases. They consist of a pyrimidine ring fused to an imidazole ring (5-membered heterocyclic) and are also aromatic. Adenine has an NH2 group at position 6 on the pyrimidine ring, while guanine has at keto group on C6 and an NH2 group on C2.
Formulae:
Adenine: C5H5N5
Guanine: C5H5N5O
Thymine: C5H6N2O2
Uracil: C4H4N2O2
Cytosine: C4H5N3O
2007-03-01 04:51:19 · answer #1 · answered by ? 2 · 0⤊ 0⤋