2. 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.
3. 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
4. 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
5. The mechanism of DNA
replication
Initiation:- formation of repliation Frok
8. 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.
