The enzyme that cleaves RNA primers formed during DNA replication is: Select one:
a. DnaA
b. DnaB
c. Primase
d. DnaG
e. RNaseH
The correct answer and explanation is:
The correct answer is e. RNase H.
During DNA replication, RNA primers are synthesized by the enzyme primase (DnaG in prokaryotes). These primers are necessary for DNA polymerase to start the process of elongating the new DNA strand. However, after the DNA strand has been extended, the RNA primers must be removed to ensure that the DNA is fully replicated. This is where RNase H comes into play.
RNase H is an enzyme that specifically recognizes and cleaves the RNA strand of RNA-DNA hybrids. In the context of DNA replication, RNase H works to remove the RNA primer, which was originally used to start the replication process. Once the RNA primer is cleaved, DNA polymerase can fill in the resulting gap with DNA nucleotides, ensuring the newly synthesized strand is continuous and composed solely of DNA.
The process of primer removal is crucial because the presence of RNA in the DNA strand would lead to improper structure and function of the newly replicated DNA. After the RNA is removed by RNase H, another enzyme, often DNA polymerase I in prokaryotes, fills in the remaining gap with the appropriate DNA nucleotides. Finally, DNA ligase seals the remaining nick to complete the strand.
In summary, RNase H is responsible for removing the RNA primers during DNA replication by cleaving the RNA strands of RNA-DNA hybrids, ensuring the DNA strand is fully formed.