The document discusses genetic recombination in bacteria, which occurs through three main processes: conjugation, transformation, and transduction. Conjugation involves the transfer of genetic material through direct contact, transformation involves the uptake of DNA from a degraded bacterium, and transduction involves the transfer of DNA via bacteriophages. Key historical studies and steps involved in each process are outlined, highlighting their significance in bacterial genetics.

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