Question

In which direction do the DNA dependent DNA polymerases catalyse the polymerization reaction?

(a) 3’ → 5’

(b) 5’ → 3’

(c) In both the directions

(d) Is not direction dependent

The question was posed to me in my homework.

The origin of the question is The Machinery and the Enzymes for Replication of DNA in chapter Molecular Basis of Inheritance of Biology – Class 12

Answer 1

Correct answer is (b) 5’ → 3’

The explanation is: The direction for DNA dependent DNA polymerases to catalyse the polymerisation reaction is the 5’ → 3’ direction. But, in this direction of polarity, a discontinuity can be observed. These discontinuous strands of DNA can then be linked together with the help of DNA ligases. But, in the direction of 3’ → 5’ in the DNA, the replication process can be seen to be continuous.