DNA replication process
It is the process which DNA make copy of itself during cell division.
1. In DNA replication is unzip double helix structure of DNA molecule.
2. This replication is carried out by enzyme called helicase which break the hydrogen bonds holding the complementary bases of DNA together {A with T, C with G}.
3. Separations of two single strands of DNA create Y shape called replication fork. Two separated strands will act as templates for making the new strand of DNA.
4. One of strands is oriented in 3 to 5 direction {towards replication fork, this is leading strand. Other strand is oriented in 5 to 3 direction {away from replication fork}, this is lagging strand. As a result of their different orientations, two strands are
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DNA polymerase bind to leading strand and then walk along it, adding.
DNA polymerase: enzyme involved in making new DNA molecules from 4 nucleotide bases, using existing DNA as template.
7. new complementary nucleotide bases {A, C, G and T} to strand of DNA in 5 to 3 direction. This type of replication called continuous. Lagging strand:
5. Numerous RNA primer is made by primase enzyme and bind at various points along lagging strand.
6. Pieces of DNA called Okazaki fragment, is then added to lagging strand in 5 to 3 direction.
7. This sort of replication called discontinuous as Okazaki fragment will need to be joined up later.
8. Once all bases are matched up {A with T, C with G}, enzyme called exonuclease strips away primer. Gaps where primer was are then filled by yet more complementary nucleotides.
9. To make sure there is no mistake in new DNA molecule the new strand is proofread.
10. Finally, enzyme called DNA ligase seal up the sequence of DNA into two continuous double strands.
DNA ligase {enzyme that joins together two strands of DNA}
11. The result of DNA replication:
I. Two DNA molecules consisting of one new and one old chain of nucleotides.
II. This is why DNA replication is described as