D Question 23 1 pt If the DNA polymerase builds both chains from the same fork,
ID: 637225 • Letter: D
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D Question 23 1 pt If the DNA polymerase builds both chains from the same fork, how is the second strand built if DNA polymerase only synthesizes DNA one direction (5' to 3)? O The lagging strand is synthesized continuously using many short fragments, called Okazaki fragments. O The leading strand is synthesized discontinuously using many short fragments, called Okazaki fragments. O The leading strand is synthesized discontinuously using many short fragments, called Okazaki fragments. O The lagging strand is synthesized discontinuously using many short fragments, called Okazaki fragments.Explanation / Answer
If DNA polymerase builds both chains from the same fork, then the second strand is built if DNA polymerase only synthesizes DNA in one direction i.e 5' to 3'.
As DNA polymerase can synthesize only one directional DNA strand (unidirectional) but DNA is a double helix which is antiparallel in nature where one strand runs in 5' to 3' direction and other one runs in 3' to 5' direction.
As already mentioned the DNA polymerase built one direction strand i.e 5' to 3', then the other strand is built throught different methods
1) Leading strand : Where nucleotides are added one by one continously in one direction where this strand runs in 5' to 3' towards the replication fork using short fragments of DNA/RNA called Okazaki fragments.
2) Lagging strand : Where nucleotides are added discontinously in a direction which runs in 5' to 3' away from the replication fork using short fragments of DNA/RNA called Okazaki fragments. (1000-2000 nucleotides)
The leading strand is extended from one primer alone whereas lagging strand require a new primer for each and every Okazaki fragment (1000-2000 nucleotides).
The lagging strand synthesis is in opposite direction to the DNA strand growth. But it is delayed process as it should wait for the leading strand to expose the template strand for Okazaki fragments to attach by discontinous back stitching mechanism.
This shows that only 5' - 3' type of DNA polymerase require replication where DNA is synthesised on the lagging strand discontinously using many short fragments of DNA called Okazaki fragments.
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