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Multiple Choice
Why are there leading and lagging strands during DNA replication?
A
Because the DNA strands are composed of different nucleotides.
B
Because DNA polymerase can synthesize DNA in both 5' to 3' and 3' to 5' directions.
C
Because DNA polymerase can only synthesize DNA in the 5' to 3' direction.
D
Because the DNA strands are identical and replicate simultaneously.
Verified step by step guidance
1
Understand that DNA replication is a process where a double-stranded DNA molecule is copied to produce two identical DNA molecules.
Recognize that DNA polymerase is the enzyme responsible for synthesizing new DNA strands, but it can only add nucleotides in the 5' to 3' direction.
Identify that the DNA double helix is antiparallel, meaning one strand runs in the 5' to 3' direction and the other in the 3' to 5' direction.
Realize that due to the antiparallel nature of DNA, one strand (the leading strand) can be synthesized continuously in the 5' to 3' direction, while the other strand (the lagging strand) must be synthesized in short segments called Okazaki fragments.
Conclude that the presence of leading and lagging strands is due to the unidirectional activity of DNA polymerase and the antiparallel structure of DNA, necessitating different replication strategies for each strand.