Q.Which of the following bases is absent in DNA?

DNA contains adenine, guanine, cytosine and thymine; uracil is found only in RNA. Correct option (c).

Nucleic acid bases:

• DNA bases: adenine (A), guanine (G), cytosine (C), thymine (T).
• RNA bases: adenine (A), guanine (G), cytosine (C), uracil (U). …

RNA's four bases are adenine, guanine, cytosine, and uracil — thymine is found only in DNA.

DNA contains the four nitrogenous bases adenine (A), guanine (G), cytosine (C), and thymine (T). RNA also contains adenine, guanine, and cytosine, but in place of thymine it contains uracil (U), which pairs with adenine just as thymine does in DNA but lac …

A nucleoside is base + sugar; a nucleotide adds phosphate to the sugar — so the chain order is base–sugar–phosphate.

A nucleic acid strand is built up in two linking steps:

1. A nitrogenous base attaches to the sugar (a pentose — ribose or deoxyribose) at its 1′-carbon via an N-glycosidic bond, forming a nucleoside (base–sugar).
2. A phosphate group then attaches to the sugar (typically at the 5′-carbon) via a phosphoester bond, forming a nucleotide (base–sugar–phosphate). …

DNA's four bases are adenine, guanine, cytosine and thymine; RNA replaces thymine with uracil.

Both DNA and RNA use the purines adenine and guanine, and the pyrimidine cytosine. The key difference is in the second pyrimidine base: DNA uses thymine (5-methyluracil), while RNA uses uracil (which lacks the methyl group thymine has at C5). This substitution i …

RNA uses Uracil in place of DNA's Thymine.

RNA is made of the bases adenine, guanine, cytosine and uracil. Thymine is found in DNA, not RNA — in RNA, thymine's role is taken …

DNA uses thymine, not uracil; RNA uses uracil instead of thymine — this is one of the key chemical differences between the two nucleic acids.

DNA (deoxyribonucleic acid) contains four nitrogenous bases: the purines adenine (A) and guanine (G), and the pyrimidines cytosine (C) and thymine (T).

RNA (ribonucleic acid) contains the same bases except that thymine is replaced by uracil (U) — uracil lacks the methyl group present on thymine's pyrimidine ring, but otherwise base-pairs with adenine in the same way thymine does.

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