AP BIOLOGY

Detailed explanation-1: -In DNA, adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C). RNA is the same, except that adenine always pairs with uracil (A-U).

Detailed explanation-2: -In DNA/RNA base pairing, adenine (A) pairs with uracil (U), and cytosine (C) pairs with guanine (G).

Detailed explanation-3: -In RNA, however, a base called uracil (U) replaces thymine (T) as the complementary nucleotide to adenine (Figure 3). This means that during elongation, the presence of adenine in the DNA template strand tells RNA polymerase to attach a uracil in the corresponding area of the growing RNA strand (Figure 4).

Detailed explanation-4: -Uracil (U) is one of the four nucleotide bases in RNA, with the other three being adenine (A), cytosine (C) and guanine (G). In RNA, uracil pairs with adenine. In a DNA molecule, the nucleotide thymine (T) is used in place of uracil.

Detailed explanation-5: -It is important to note that in RNA (RiboNucleic Acid), adenine pairs with uracil because RNA molecules do not contain any thymine. The shape of the uracil molecule is very similar to thymine; the only difference is that uracil (formula C4H4N2O2 C 4 H 4 N 2 O 2 ) is missing a methyl group (-CH3 C H 3 ).