What happens during the replication of DNA

Polymerase, ligase, primer, primase, helicase ...

Before mitosis or meiosis can occur, a cell has to duplicate its DNA. This is done through replication during the interphase.

Replication process:
1. The enzyme topoisomerase unwinds the DNA double helix.
2. The helicase then cleaves the double strand of DNA that has now been spiralized into two single strands by breaking the hydrogen bonds of the opposing base pairs while consuming ATP.
3. The primase synthesizes so-called primers at the 3 'ends, which are necessary for the start of the actual replication and serve as a starting point.
4. At the 3 'end of the primer, the DNA polymerase begins to synthesize complementary bases, creating a new DNA double strand.
However, the DNA polymerase can only run from 5 'to 3'. This means that on the antiparallel strand (3 'to 5') the synthesis has to take place in the opposite direction. And that only works if new primers are set again and again. In this way, individual synthesized pieces of DNA, the so-called Okazaki fragments, are created between the primers. One also speaks of a discontinuous formation of the DNA strand.
5. RNase H now removes the RNA primers from the DNA and another DNA polymerase closes the resulting gaps with complementary bases.
6. Finally, the enzyme ligase links the discontinuously formed strand through ester bonds.

As a result, two identical strands of DNA have now emerged.