Question

Explain the process of DNA replication with the help of a schematic diagram.

Answer 1

DNA Replication
DNA replication is the phenomenon in which a duplicate copy of DNA is synthesised.

The steps involved in the process of DNA replication are as follows:

• DNA replication occurs in S-phase of the cell cycle.

• Enzyme involved: DNA polymerase (DNA dependent DNA polymerase)

• Replication requires energy.
  Source of energy −Deoxyribonucleoside triphosphates (DNTPs)

• DNTPs have dual purposes: act as substrates as well as provide energy

• Replication initiates at specific regions in DNA called the origin of replication.

• DNA polymerase polymerises a large number of nucleotides in a very short time.

• During the course of replication, two parent strands do not completely open, but a small opening forms in which replication occurs. This small opening forms a replication fork.

• DNA polymerase can polymerise only in one direction, i.e., 5'→3'.

• Therefore, replication occurs smoothly in 3'to 5'end of DNA (continuous replication, but occurs discontinuously in 5' to 3'end).

• The discontinuous fragments so formed are joined by DNA ligase.