Structure of RNA Bases

RNA bases are similar to those of DNA, except for the fact that in RNA molecules, uracil is present instead of thymine. Uracil differs from thymine in that the methyl group on the 5’ carbon is replaced by a hydrogen atom, as shown. The other three bases found in RNA consist of adenine, cytosine, and guanine, and are identical to those found in DNA. In this animation, hydrogen atoms are shown in white, carbon in grey, oxygen in red, and nitrogen in blue.

Question 1: ___________ is present instead of thymine in RNA.
  1. guanine
  2. thymine
  3. cytosine
  4. uracil


Answer 1 Answer - (d) Uracil

Question 2: What is the difference between thymine and uracil?
  1. The hydrogen group on the 5’ carbon is replaced by a methyl group.
  2. The thymine is a different color than the uracil.
  3. The methyl group on the 5’ carbon is replaced by a hydrogen atom.
  4. The methyl group on the 3’ carbon is replaced by a hydrogen atom.


Answer 2 Answer - (c) The methyl group on the 5' carbon is replaced by a hydrogen atom