Which base is characteristically used in DNA and is not typically found in RNA?

Which base is characteristically used in DNA and is not typically found in RNA?

• A. Thymine
• B. Uracil
• C. Cytosine
• D. Adenine

Answer: (A)

Thymine is the base associated with DNA. In DNA, the bases are adenine, thymine, cytosine, and guanine, with thymine pairing with adenine. RNA uses uracil instead of thymine, pairing with adenine, because its backbone is ribose rather than deoxyribose and it serves short‑lived, coding roles. The methyl group on thymine helps stabilize the DNA molecule and also helps the cell distinguish true thymine from uracil that could arise from cytosine deamination, guiding repair processes. So thymine is characteristic of DNA and isn’t typically found in RNA.

Thymine is the base associated with DNA. In DNA, the bases are adenine, thymine, cytosine, and guanine, with thymine pairing with adenine. RNA uses uracil instead of thymine, pairing with adenine, because its backbone is ribose rather than deoxyribose and it serves short‑lived, coding roles. The methyl group on thymine helps stabilize the DNA molecule and also helps the cell distinguish true thymine from uracil that could arise from cytosine deamination, guiding repair processes. So thymine is characteristic of DNA and isn’t typically found in RNA.