Rolling circle replication is a process of unidirectional nucleic acid replication that can rapidly synthesize multiple copies of circular DNA or RNA molecules such as plasmids. It involves nicking a circular double-stranded DNA molecule, elongating the 3' end to form the leading strand while displacing the 5' end to form the lagging strand of Okazaki fragments. The displaced single-stranded DNA then circulates and synthesizes its own complementary strand, resulting in replication of both the original nicked and displaced strands in a rolling motion. Examples include replication of circular plasmids in bacteria and certain viruses like herpesvirus, papillomavirus, and geminivirus.

1. ROLLING CIRCLE
OF
REPLICATION
By,
T.Sathya
MSC MICROBIOLOGY
(2017-2019)
Tirupur Kumaran College
for Women, Tirupur

3. INTRODUCTION:
*Rolling circle replication is a process of
unidirectional nucleic acid replication.
* can rapidly synthesize multiple copies of circular
molecules of DNA or RNA, such as plasmids.
* Eucaryotic also replicate.
* widely used in molecular biology & biomedical
nanotechnology, especially in the field of
biosensing (as a method of signal Amplification).

4. What are the steps
for Rolling Circle
Replication

5. STEPS:
1) Circular ds DNA will be “nicked”
2) 3` end is elongated →Leading strand
3) 5` end displaced → Lagging strand
made up of double stranded by OKAZAKI
fragments.
4) Replication of both “ unnicked” and displaced ss
DNA
5) Displaced DNA circulates and synthesis its own
complementary strand.

7. → Replication in eucaryotes is bidirectional, this type
is Unidirectional.
→Ideal example of this type is the circular plasmid
is bacteria, as it happens only in circular genomes.
Initiation
Initiates
- phosphate ends, by the action of:
a) Helicase
b) Topoisomerases
c) Single stranded binding proteins(SSBPs).

8. Elongation
→ For Elongation,
- OH group of broken strand, using the unbroken
strand as a template. The polymerase will start to move
in a circle for elongation, due to which it is named as
Rolling Circle Model.
end will be displaced and will grow out like a
waving thread.

9. Termination
* At the point of termination, the linear DNA
molecule is cleaved from the circle resulting in a double
stranded circular DNA molecule and a single- stranded
linear DNA molecule.
* The linear single stranded molecule is circularized by
the action of ligase and then replication to double stranded
circular plasmid molecule.

14. Replication starts at ORI
region by a initiator Rep A
Region binds with DNA Polymerase and
replication starts.

15. Helicase also attaches to the
region
Progeny positive strands
synthesis

16. Positive strands also synthesis its
complementary synthesis

17. Breakage is
joining
by Ligase
Progeny strand can also synthesis
another strand of DNA

18. Overall explanation of
Rolling Circle:

20. Example:
Viral DNA
* Human herpes virus
* Human papilloma virus
* Geminivirus
Viral RNA
* pospiviridiae
* Avsunviridiae

21. Refference:
•https://en. m. wikipedia.org
• what- when- how.com
• https//www.sciencedirect.com
• www.slideshare.com
•Genetics-notes.wikispace.com
• you tube
• Prescott 5th edition page.no: 236, 237
• Brock biology of microorganism , page.no:
253,616