AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA REPLICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The lagging strand is the new strand that grows discontinuously away from the replication fork.
A
True
B
False
Explanation: 

Detailed explanation-1: -One strand is synthesized continuously in the direction of the replication fork; this is called the leading strand. The other strand is synthesized in a direction away from the replication fork, in short stretches of DNA known as Okazaki fragments. This strand is known as the lagging strand.

Detailed explanation-2: -The “lagging strand” is synthesized in the direction away from the replication fork and away from the DNA helicase unwinds. This lagging strand is synthesized in pieces because the DNA polymerase can only synthesize in the 5′ to 3′ direction, and so it constantly encounters the previously-synthesized new strand.

Detailed explanation-3: -Due to the functional restriction of the DNA polymerase not being able to synthesize the chain in 3’ to 5’ direction, on the lagging strand, the synthesis of the chain is discontinuous in the 5’ to 3’ direction. The discontinuous replication results in several short segments which are called Okazaki fragments.

Detailed explanation-4: -Steps of the discontinuous DNA replication reaction. The leading strand is synthesized continuously while the lagging strand is synthesized discontinuously.

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