Question

Okazaki fragments are

• A. RNA primers
• B. Short DNA fragments on leading strand
• C. Short DNA fragments on lagging strand
• D. DNA fragments from dimerization

Answer 1

Answer: (C)

Short DNA fragments on lagging strand

RNA primer is a stranded segment (complementary to the template) and has a free 3’ hydroxyl group to facilitate the addition of nucleotides by polymerase enzymes; option A is incorrect. The leading strand synthesis proceeds continuously from a single RNA primer in the 5'-->3' direction and there are no short fragments formed on it during replication which makes option B wrong. To facilitate the growth of the lagging strand in the 5'-->3' direction, a new primer is added every few hundred bases on the second parental strand. Each of these primers is elongated in the 5'-->3' direction and form discontinuous segments called as Okazaki fragments which are later joined together by DNA ligase; option C is correct. Ultraviolet light causes DNA dimerization by introducing pyrimidine dimers which are then repaired by DNA repair mechanisms; option D is incorrect.

Thus, the correct answer is option C.