Biomolecules Question 54
54. RNA does not possess
(a) Uracil
(b) Thymine
(c) Adenine
(d) Cytosine
Show Answer
Answer : b
Hints & Solutions
(b) In RNA, pyrimidine thymine is replaced by uracil.
Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA. In DNA, however, uracil is readily produced by chemical degradation of cytosine, so having thymine as the normal base makes detection and repair of such incipient mutations more efficient.
