Question

Identify the CORRECT combination of statements with respect to DNA synthesis.

I. Always the direction of DNA polymerization 5' → 3' when referring to the polarity of strand being synthesized.

II. DNA ligase forms hydrogen bonds between two newly synthesized DNA strands.

III. DNA polymerases on their own cannot initiate the process of replication.

IV. DNA polymerase can catalyse polymerization in both 5'→ 3' and 3'→ 5' direction.

Options

• III and IV

• I and II

• I and III

• II, III and IV

Answer 1

I and III

Explanation:

Phosphodiester linkages are formed by DNA ligase between two consecutive nucleotides of a newly produced DNA strand. Only the 5' → 3' route of DNA polymerization can be catalysed by DNA polymerase.