In vitro DNA replication is also semiconservative but there

In vitro DNA replication is also semi-conservative, but there are no Okazaki fragments. Why do you think that is?

A. Because DNA polymerase has both 3’->5’ and 5’->3’ polymerase activity in vitro.

B. Because there is no replication bubble in vitro.

C. Because no primers are needed in vitro.

D. Because DNA polymerase works at a higher speed in vitro.

Solution

In vitro DNA replication (replication o utside the cell) is alos possible. The primers are used to extend specific target sequences of DNA and DNA polymerase adds the new nucleotides to the extending polynucleotide chain. Generally, Okazaki fragments are producedduring replication when one of the DNA strands is replicated in short segments. This strand of DNA is also known as lagging strand and later DNA ligase fills the gaps forming a continuous strand. In vitro, the DNA polymerase is efficient in synthesizing nucleotides in both 3\' to 5\' and 5\' to 3\' directions at a rapid rate without the replication bubble. Therefore, Okazaki fragments are not produced. This type of DNA replication is observed in polymerase chain reaction (PCR) where the DNA sequences are amplified within short period. Option B is correct.