In RNA, thymine is replaced with which base?

In RNA, thymine is replaced with which base?

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

Answer: (B)

RNA uses uracil in place of thymine. Thymine is the methylated form of uracil, and its use in DNA helps protect the genetic material and aids repair by allowing enzymes to distinguish natural bases from deamination events. Because RNA is typically single-stranded and short-lived, it doesn’t need that extra methyl group, so uracil is used instead to pair with adenine during transcription. In this pairing, A matches with U (just as A pairs with T in DNA). The other bases—adenine, guanine, and cytosine—are still part of RNA, but thymine isn’t; it’s replaced by uracil.

RNA uses uracil in place of thymine. Thymine is the methylated form of uracil, and its use in DNA helps protect the genetic material and aids repair by allowing enzymes to distinguish natural bases from deamination events. Because RNA is typically single-stranded and short-lived, it doesn’t need that extra methyl group, so uracil is used instead to pair with adenine during transcription. In this pairing, A matches with U (just as A pairs with T in DNA). The other bases—adenine, guanine, and cytosine—are still part of RNA, but thymine isn’t; it’s replaced by uracil.