What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

Question:- What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

Select one:

1:- It is involved in the lengthening of telomeres

2:- It adds nucleotides to the leading strand

3:- It unwinds the DNA double helix.

4:- It joins Okazaki fragments together

5:- It synthesizes RNA nucleotides to make a primer

Answer:-  4. It joins Okazaki fragments together

DNA ligase is involved in lagging strand elongation and the role it plays involves joining together blocks known as Okazaki fragments, which are synthesized short stretches in 3’ to 5’.

As the DNA polymerase synthesizes these fragments, there is space between each fragment. DNA ligase seals these gaps by enzymatically polymerizing phosphodiester bonds between the 3’ hydroxy end of one Okazaki fragment and the 5′ phosphate end of another. This combines the fragments into a continuous thread.

The other options do not describe the role of DNA ligase:

• It does not participate in telomere elongation.
• It does not polymerize nucleotides or incorporate them into the leading strand.
• It does not uncoil the DNA double helix.
• It does not produce RNA primers.

Thus, the correct function of DNA ligase in lagging strand elongation is to direct phosphodiester bonds between Okazaki fragments by catalysing their joining. This ties them into a continuous DNA strand.