Question

Assertion (A) Replication on one strand of DNA is continuous and on another it is discontinuous.
Reason (R) The DNA polymerase works in $3' \rightarrow 5' $ direction.

• A. If both A and R are true and R is the correct explanation of A
• B. If both A and R are true, but R is not the correct explanation of A
• C. If A is true, but R is false
• D. If A is false, but R is true

Answer 1

Answer: (A)

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
The DNA-dependent DNA polymerase works in the $5' \rightarrow 3'$ direction requiring a free $3'-OH$ of a pre-existing polynucleotide for initiating DNA replication. Thus, it continuously synthesises the strand
having polarity $3' \rightarrow 5'$
Replication of the lagging strand $(5' \rightarrow 3')$ generates small polynucleotide fragments, okazaki fragments. The replication of this strand is discontinuous.