Recombination in prokaryotes

1. UNDER THE GUIDANCE OF
Mrs Asha .S.K
LECTURER,
PG Dept of Biotechnology,
Sahyadri Science College,
Shivamogga.
KUVEMPU UNIVERSITY
P.G. DEPARTMENT OF BIOTECHNOLOGY
SAHYADRI SCIENCE COLLEGE
A SEMINAR TOPIC ON,
“RECOMBINATION IN PROKARYOTES”
PRESENTED BY:
SAHANA .C.M
1st MSc I Sem
Dept of Biotechnology,
Sahyadri Science College
Shivamogga.

2. CONTENTS :-
• INTRODUCTION
• TYPES OF RECOMBINATION IN PROKARYOTES
• TRANSFORMATION
• CONJUGATION
• TRANSDUCTION
• CONCLUSION
• REFRENCE

3. INTRODUCTION :-
• RECOMBINATION – It is defined as “ The process of rearrangement
or reshuffling of genetic material”.
• “It may be the transfer of genes from one cell to the another to get
improved genetic characteristics”.
• Occurs in nearly in all multicellular organisms.

4. TYPES OF RECOMBINATION :-
There are mainly , 3 Types of genetic
recombination in prokaryotes they are ;
• Transformation
• Conjugation
• Transduction

5. TRANSFORMATION:-
• “The process of transfer of genetic information into
the recipient cell in the form of exogenous DNA
extracted from donor cells”.
• Discovered by Frederick Griffith in 1928 in
S.pneumoniae.

6. HE USED TWO STRAINS OF BACTERIA : R STRAIN AND S STRAIN
• He concluded that, the heated S Strain which
acts as non-pathogenic enables the living R
Strain to make capsule around it.
• Living R strain and heated S strain can be
transferred into living S strain.
• From this experiment he conclude that DNA
was the genetic material.
Griffith’s Transformation Experiment

7. MECHANISM OF TRANSFORMATION
Transformation is the process of transfer of genetic information into the
recipient cell in the form of exogenous DNA extracted from donor cells.

8. CONJUGATION:
• It is a process of where the DNA is transferred from donor to
recipient by cell to cell contact.
DISCOVERY OF CONJUGATION:
• This type of genetic transfer was first proposed by Lederberg and
Tatum in 1946.
• They used two Auxotrophic strains of E-coil one strain requires
biotin, phenylalanine, and cytosine but it could synthesize
Threonine, Leucine and Thymine.
• These two strains are not capable of growing on minimal media.
They mix these two strains and cultivated them in a complete
medium.

9. DAVIS’ U-TUBE EXPERIMENT :

10. MECHANISM OF BACTERIAL CONJUGATION:
• 1. F+ CROSS F-
CONJUGATION:

11. HFR CONJUGATION
1.F plasmid can also integrate two chromosome
DNA, such cells are called as episome.
2.It refers to the relatively high frequency with
which the donor genes are transferred to the
recipient.
3. Integrated F mediates the transfer of DNA from
bacterial chromosomes in Hfr cell .
4.When a culture of HFR cell mixed with a F- culture
conjugation, conjugation occurs the integrate F
factor is nicked at its set of a origin of transfer (Ori-
T) this point is same at which the replication and
transfer begin in an unintegrated F-plasmid.

12. F1 * F- CONJUGATION
• In the Hfr cells , sometimes the plasmid is disintegrated from the chromosome
during this the plasmid makes an error and picks up a portion of the
chromosomal material to form the F1 plasmid and the cell is F1 cells.
• When the conjugation occurs between F1 and F- cells the plasmid is transferred
along with some genes of chromosome.
• In this way specific bacteria genes may spread throughout a bacterial
population such a transfer of bacterial gene is offen called F duction.

13. TRANSDUCTION:
• Transduction in bacteria was discovered
by Zinder and Lederberg in 1952.
• In this mechanism , Transduction occurs
when a phage (virus) carries bacterial
gens from one host cells to another.
• It is the phenomenon is which the
bacterial DNA is transferred from one
bacterial cell to another by a
bacteriophage.
• Two different types of transduction are
known
• Generalized transduction
• Specialized transduction

14. • *Generalised transduction:- The process by which phage can package any bacterial
DNA
[ chromosomes or plasmid ] and transfer it to another bacterium.
• Depending on this transduction is of 2 types.
1 . Complete transduction :- During this process the exogenome is introduced into the
recipient cell by a transduction.
• Pairing and crossing over occurs between the exogenome and endo genome to
produce recombinant DNA .
• 2 . Abortive transduction:- when the exogenome is not inserted into the bacterial
chromosome it result in abortive transduction .
*Specialised transduction:-
Here the transduction particle carries only specific portions of the of the bacterial
genome.
This occurs in the case of life cycle of template phage .

15. MECHANISM OF TRANSDUCTION

16. CONCLUSION:-
• Genetic recombination is a well-studied mechanism responsible for
providing genetic diversity in eukaryotic and prokaryotic cells.
• Recombination also plays an important roles in DNA repair .

17. REFERENCE
• Ajoy paul ‘’Genetics’’ Second Edition. Page no 374 -383.
• P.S Verma and V .K .Agarwal ‘’Genetics’’ S. Chand
Publication 9th Edition.

18. THANKYOU!!