Explain why half of DNA is replicated in a discontinuous fashion. Replication of

Question

Explain why half of DNA is replicated in a discontinuous fashion.

Replication of the lagging strand occurs in the direction away from the replication fork in short stretches of DNA, since access to the DNA is always from the 5’ end. This results in pieces of DNA being replicated in a discontinuous fashion.

b

Replication of the leading strand occurs in the direction away from the replication fork in short stretches of DNA, since access to the DNA is always from the 5’ end. This results in pieces of DNA being replicated in a discontinuous fashion.

c

Replication of the lagging strand occurs in the direction of the replication fork in short stretches of DNA, since access to the DNA is always from the 5’ end. This results in pieces of DNA being replicated in a discontinuous fashion.

d

Replication of the lagging strand occurs in the direction away from the replication fork in short stretches of DNA, since access to the DNA is always from the 3’ end. This results in pieces of DNA being replicated in a discontinuous fashion.

Explanation / Answer

The replication of DNA always occurs on the template which is in 3' to 5' direction. The resulting daughter strand will be in 5' to 3' direction. Thus the access to template in always in 3' side and the polymerase cannot initiate replication, if 5' side is open. During DNA replication, the two strands separate one with 5' end and another with 3' end. The starnd which is open at 3' end can initiate replication in the direction of the replication fork,This is called leading strand. Another strand which has 5' end, cannot begin replication, this is called lagging strand. A short strands are replicated in opposite side. This forms the fragmented replication creating okazaki fragment. Hence the lagging strand replication occurs in direction away from the replication fork as the DNA is accessible only from 3' end.

Option D is the answer.

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