Genetic Recombinition in Bacteria
- 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.
- 9. . 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.
- 15. . 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.
- 16. . 4. The bacteriophages are released. 5. The bacteriophage carrying the donor bacterium's DNA adsorbs to a recipient bacterium
- 17. . 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 .
- 19. . 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.
- 20. . 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.
- 21. . 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.
- 23. . THANKS