Question

Why is there a problem replicating the ends of linear DNA?

Group of answer choices

Leading strand synthesis primed at the replication origin of a linear DNA can’t remove and replace the primer.

Lagging strand synthesis primed at the ends of a linear DNA can’t be removed and replaced because there is no 3'-OH available.

Since replication only initiates at the ends of linear DNA, the priming of each leading strand leaves a primer at the end that cannot be removed.

Primase cannot copy telomere DNA.

Answer 1

Second answer is correct. The DNA at the end in linear DNA molecules has problem replicating at the ends. The leading strand is replicated fully but I lagging strand needs primers that are extended by DNA polymerase forming okazak fragments. At the end of a replication when RNA primer at the - end is removed, DNA replication can't - proceed in absence of brimer. So DNA molecule would be shortened. To overcome I this problem enzyme telomerase extendo 3' end of telomere (telomeres CS are present at end of chromosome) Isl.Scanned with

and allows DNA replication machinery - to completely replicate lagging strand Scanned with Cam Scanner