Question

How many stages are there in DNA replication?

Answer 1

DNA replication:

1. DNA replication is the process where the genetic material of the cell is duplicated.
2. It helps in maintaining genetic continuity and inheritance of the genome from parents to offspring.
3. DNA duplication occurs in the S-phase of the cell cycle.
4. The replication process ensures that each daughter cell receives a copy of DNA.
5. The process of DNA replication is catalyzed by many different enzymes.
6. DNA is made up of two different strands which separate and act as a template for the enzymes to synthesize a new complementary DNA strand.
7. It is a semi-conservative process, i.e., after each cycle of replication one strand of DNA is parental and the other is new.
8. The semi-conservative nature of DNA was proved by the Meselson and Stahl experiment.
9. DNA replication consists of three major steps.

A. Initiation:

1. It is the step where the helicase opens up the two strands.
2. The replication fork is formed at the origin of replication.
3. The DNA polymerase enzyme assembles at the template strand.

B. Elongation:

1. The elongation step consists of the synthesis of a new DNA strand by the DNA polymerase enzyme on the template strand known as the leading strand.
2. The polymerization occurs in the 5'-3' direction in a continuous manner.
3. Whereas in the lagging strand the polymerization occurs in an incomplete fashion and Okazaki fragments are formed.

C. Termination:

1. The termination of polymerization occurs when the replication fork reaches the termination signals such as the TER signal, etc.
2. The discontinuous Okazaki fragments are ligated via the DNA enzyme ligase.