DNA REPLICATION BY ARIHANT JAIN

1. JAIPUR NATIONAL UNIVERSTY,
JAGATPURA,JAIPUR
Name :-Arihant jain
Department of life
science
M.Sc. Microbiology
2nd Semester

3. DNA

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13. Replication of eukaryotes
 Chromosome of eukaryotes have multiple origins.
 The space between 2 adjascent origins is called the
replicon, a functional unit of replication.
 Orgin of DNA replication (every-150 kb)

14. Semi-continuous Replication
 The daughter strands on 2 template strands are
synthesized differently since the replication process
obeys the principle that DNA is synthesized from the
5’ to the 3’ end.
 OKAZAKI FRAGMENTS:-Many DNA fragments are
synthesized sequentially on the DNA template
strand having the 5’ end. These DNA fragments are
called Okazaki fragments. They are 100-150
nucleiotide long for eukaryotes

15. continuouslyin the 5’-3’ direction. This
strand is referred as the leading strand.
The daughter strand consisting of
okazaki fragments is called the lagging
strand.
Continuous synthesis of the leading
strand & discontinuous synthesis of
lagging strand represent a unique
feature of DNA replication,its referred as
semi-continuous replication.

18. Primase (DnaG)
 Primase is able to synthesize
primers using free NTPs as
the substrate & the ssDNA as
the template.
 Primers are short RNA
fragments of a several
decades of nucleotides long.

19. Helicase (DnaB)
 It opens the dsDNA with consuming ATP.
 The opening process with the assistance of DnaA &
DnaC

20. SSB Protein
 Stand for ssDNA binding protein.
 SSB Protein maintain the DNA Template in the single
strand form order to
 -prevent the ds DNA formation;
 -protect the vulnerable ssDNA from
 nucleases.

21. Topoisomerase
 Opening the ds DNA
will create supercoil
ahead of replication
forks.
 The supercoil
constraint needs to
be released by
topoisomerase.

22. DNA Ligase
 Connect 2 adjascent
ssDNA strands by
joining the 3’-OH of
one DNA strand to the
5’-P of another DNA
strand.
 Sealing the nick in the
process of replication
, repairing,
recombination &
splicing

23. Replication Fedelity
 Replication based on the
principle of base pairing is
crucial to the high accuracy
of the genetic information
transfer.
 Enzymes use 2 mechanism
to ensure the replication
fidelity.
-Proofreading & real-time
correction
-Base selection

25. DNA Replication in Eukaryotes
 DNA replication is closely related with the cell cycle.
 Multiple origin on 1 chromosome replications are
activated in a sequential order rather than
simultaneously

26. INITIATION

27. Elongation

28. Termination

30. Telomerase
Significance of
telomerase:-
Telomerase may play
important role in
cancer cell biology &
in cell aging

31. References:-
 Book reference:-

33. THANK
YOU