BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Uracil is present only in RNA, whereas thymine is present only in DNA. Thus, thymine is the nitrogenous base which is not present in RNA.

Detailed explanation-2: -Four different types of nitrogenous bases are found in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, the thymine is replaced by uracil (U).

Detailed explanation-3: -Adenine and guanine are found in RNA and DNA in terrestrial life, whereas thymine is only found in DNA and uracil only in RNA.

Detailed explanation-4: -In RNA, the base thymine is not found and is instead replaced by a different base called uracil, abbreviated U; the other three bases are present in both DNA and RNA.

Detailed explanation-5: -However, since mRNA is relatively short-lived and any potential faults don’t result in any lasting damage, RNA employs uracil because the instability doesn’t matter as much for RNA. Thymine is also quickly oxidized. The thymine in the nucleus is shielded from oxygen.