this presentation is about reproduction of bacteria also known as genetic recombination. it consist of three types i.e. transformation, transduction and conjugation.

2. GENETIC RECOMBINITION IN BACTERIA
Prepared by : SAFI ULLAH
Roll No: B-11
BS: BOTANY
5th semester Student

3. INTRODUCTION
 Genetic recombination is the process by which “Exchange of genes between
two DNA molecules to form new combinations of genes on a chromosome.
 In bacteria genetic recombination can happen three ways;
 1. Conjugation
 2.Transformation
 3.Transduction

4. 1.Conjugation
 Transfer of genetic material from one bacteria to another bacteria by physical
contact is called conjugation.
 Bacterial conjugation is the transfer of genetic material (plasmid) between
bacterial cells by direct cell-to-cell contact or by a bridge-like connection
between two cells.
 Bacterial conjugation are discovered by “Joshua Lederberg and Edward
Tatum” in 1946.

7. 2.Transformation
 Genetic recombination in which a DNA fragment from a dead_degraded
bacterium enters a competent recipient bacterium and it is exchanged for
a piece of the recipient's DNA.
 The phenomenon of transformation was first recorded by Griffith (1928).
 First time demonstrated this phenomenon in streptococcus pneumoniae.

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 Transformation involves four steps;
 Step 1. A donor bacterium dies and is degraded.

10. Step 2
 A fragment of DNA from the dead donor bacterium binds to DNA binding
proteins on the cell wall of a competent, living recipient bacterium

11. Step 3
 The Rec A protein promotes genetic exchange between a fragment of the
donor's DNA and the recipient's DNA.

12. Step 4
 Exchange is complete.

13. 3.Transduction
 Genetic recombination in which a DNA fragment is transferred from one
bacterium to another by a bacteriophage.
 Transduction in bacteria are discovered by Lederberg and Zinder in 1951.
 Two types of transduction occurs in bacteria;
 Generalized transduction.
 specialized transduction.

14. Generalized transduction
 A DNA fragment is transferred from one bacterium to another by a lytic
bacteriophage that is now carrying donor bacterial DNA due to an error in
maturation during the lytic life cycle.
 There are seven steps of generalized transduction;
 1. lytic bacteriophage adsorbs to a susceptible bacterium.

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 2. The bacteriophage genome enters the bacterium. The genome directs
the bacterium's metabolic machinery to manufacture bacteriophage
components and enzymes.
 3. A bacteriophage head or capsid assembles around a fragment of donor
bacterium's nucleoid or around a plasmid instead of a phage genome by
mistake.

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 4. The bacteriophages are released.
 5. The bacteriophage carrying the donor bacterium's DNA adsorbs to a
recipient bacterium

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 6. The bacteriophage inserts the donor bacterium's DNA it is carrying into
the recipient bacterium.
 7. The donor bacterium's DNA is exchanged for some of the recipient's
DNA.

18. specialized transduction
 A DNA fragment is transferred from one bacterium to another by a
temperate bacteriophage that is now carrying donor bacterial DNA due
to an error in spontaneous induction during the lysogenic life cycle.
 There are sex steps for specialized transduction;
 1. A temperate bacteriophage adsorbs to a susceptible bacterium and
injects its genome .

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 2. The bacteriophage inserts its genome into the bacterium's nucleoid to
become a prophage.
3. Occasionally during spontaneous induction, a small piece of the donor
bacterium's DNA is picked up as part of the phage's genome in place of some
of the phage DNA which remains in the bacterium's nucleoid.

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 4. As the bacteriophage replicates, the segment of bacterial DNA
replicates as part of the phage's genome. Every phage now carries that
segment of bacterial DNA.
 5. The bacteriophage adsorbs to a recipient bacterium and injects its
genome.

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 6. The bacteriophage genome carrying the donor bacterial DNA inserts
into the recipient bacterium's nucleoid.

22. REFERENCES
 https://www.slideshare.net/krishnashah5891004/recombination-in-bacteria-
88117548.
 https://www.sciencelearn.org.nz/resources/2032-bacterial-transformation.
 http://www.yourarticlelibrary.com/biology/3-ways-in-which-the-genetic-
recombination-in-bacteria-takes-place/3941.
 https://en.wikipedia.org/wiki/Bacterial_recombination.
 http://www.biologydiscussion.com/bacteria/genetic-recombination-of-
bacteria-with-diagram/47074.

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THANKS