DNA REPLICATION

Presentation by: Bhavani Meena

DNA REPLICATION

Dna raplication is a mean to produce new molecule that have the same base sequence.

Occurs in S phase of cell cycle.

Each unpaired nucleotide will attract a complementary

nucleotide from the medium.

Enzymes Used in Replication

1. Topoisomerase:- removing the coiling tension

2. Helicase :- melting (cuting) of Hydrogen bonds

3. Primase:- synthesis of RNA primers

4. Rnase:- removel of rna primer

5. Ligase:- formation of phosphodiester bond

6. Single-Stranded Binding Proteins :- maintain the stability of replication fork

7. DNA polymerase:- it is the most important enzyme of in

DNA Replication it has three types.a. DNAPOLI :-

5` → 3` Polymerase activity

5` → 3` exonuclease activity

3` → 5` proof-reading exonuclease activity

b. DNAPOLII :-

DNA-duplex with gaps and cannot replicate long strands

c. DNAPOLIII :-

Polynucleotide chain polymerisation

Proof reading and DNA repairing

The mechanism of DNA replication

Initiation:- formation of repliation Frok

Elongation

This phase includes leading and lagging strand synthesis

Termination

Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points.

Ter – Sequences have some protein called Tus – proteins (Terminus Utilisation Substances).

These Ter – sequences having Tus protein form a complex that inhibit or terminate the replication fork from one direction.

Newly synthesized DNA

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