During DNA replication, the DNA makes copies of itself. This happens during the S phase of cell cycle. The replication starts in specific parts of DNA called “origins of replication.” DNA helicase- is an enzyme that opens or unzips the double helix so there are two strands ready to be replicated. SSBP are proteins that keep the strands apart from each other, and DNA topoisomerase deals with the twisting problem. the replication starts when an RNA primer attaches to the origins (because free nucleotides can not attach unless there is something to hold to). Then DNA polymerase starts attaching nucleotides to the strands so A pairs with T and G with C. it is important to mention that the replication only occurs in 5’ to 3’ direction. As we know the DNA strands are twisted in opposite direction (on in 5’ to 3’ and the other in 3’ to 5’ direction). So in one strand, DNA polymerase continuously adds nucleotides to make the new DNA. This process is fast and this is called the leading strand. But on the strand the DNA polymerase has to work kind of backwards because it has to go on the other direction in order to replicate from 5’ to 3’ direction. This is a discontinoual process and this is the lagging strand. The DNA that is made is fragmented in so called “okazaki fragments.” When the process is stoped, DNA ligase links these fragments and the DNA is replicated in two identical copies.
Mohaissack answered the question on October 4, 2017 at 08:48
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