transduction

transduction is a process which that bacteriophage is transfer the genetic material to one to another bacterial cell .the transduction is have a two types that is generalized and specialized transduction .the two types of phage will be involve in the transduction process that is virulant and temptate pahge

1. By SWETHA MOHAN.S I-Msc., Microbiology TRANSDUCTION

2. DEFINITION: The transfer of genetic material from one cell to another cell by a bacteriophage is called Transduction. Transduction has been found to occur in variety of prokaryotes , including certain species of Bacteria : e.g : Escherichia , Pseudomonas , Salmonella , Staphylococcus , etc. The bacteriophage containing the bacterial DNA is called transduced DNA .

3. Transduction was first discovered by Norton Zinder and Joshua Lederberg in 1952. Joshua Lederberg Norton Zinder 2 History:

4. Studied in Salmonella typhimurium Plated two auxotrophic strains ( LA-2 and LA-22 ) individually on minimal medium, no cells grew. Pl a ted a mixture of t he two auxotr o ph i c s t ra i ns on min i mal medi u m, c e l l s gr e w i n to c o l on i e s . Thus, genetic exchange was taking place between two cell types.

5. U-Tube Experiment

6. Types of Bacteriophage: VIRULENT : Capable of causing infection eventually destruction and death of the bacterial cell . These follow LYTIC CYCLE . Example : T4 host E.coli . TEMPERATE : Does not cause destruptic infection instead phage DNA incorporated into bacterial DNA and replicate (LYSOGENIC)and after some cycle become virulent cause lysis . Example : lamda phage .

7. There are TWO types of transduction 1. Generalized transduction A DNA f r a g me n t is t r an s f er r ed f r om one bac t e r i u m t o another b y a lytic bac t e r io p ha g e(v i ru l e n t) wh i ch c arrying donor • bacterial DNA due to an error . • 2. Specialized transduction A DNA fragment is transferred from one bacterium to another by a temperate bac t e r iop h a g e which c arrying donor DNA a l ong with phage genome due to an error .In this a phage insert a genome at specific site. TYPES OF TRANSDUCTION:

8. Generalized: Transduction in which potentially any donor genes can be transferred.

9. GENERALIZED TRANSDUCTION: Infect the host cell The bacteriophage genome enters the ba c terium.

10. Bacteriophage (carries a host DNA) attach to the recipient cell

11. The bacteriophage inserts the donor bacterium's DNA it is carrying into the recipient bacterium . The donor bacterium”s DNA exchange the some of the recipient bacterium”s DNA

12. EXAMPLE:

13. Specialized: Transduction in which only certain donor genes can be transferred.

14. SPECIALIZED TRANSDUCTION: A temperate bacteriophage attach to the host cell and inject there genome The bacteriophage inserts its genome into the bacterium's nucleoid to become a prophage.

15. Occasionally during spontaneous indu c tion, a small pie c e of the don o r ba c terium's D N A is pi c k e d up as pa r t of the pha g e's gen o me in place of s o me of the pha g e D N A whi c h remains in the bacterium's nucleoid. As the bacteriophage replicates, the segment of bacterial D N A replicates as pa r t of the pha g e's gen o me. E v e r y pha g e now c a r r ies that s e gment of ba c terial D N A.

16. The bacteriophage genome carrying the donor bacterial DNA inserts into the recipient bacterium's nucleoid. The bacteriophage adsorbs to a recipient bacterium and injects its genome.

17. Signi f i c ance of t r ansduction: It transfers genetic material from one bacterial cell to another and alter the genetic characteristics. For example: In specialized transduction the gal gene, a cell lacking ability to metabolize galactose could aquire the ability . It shows the evolutionary relationship between the prophage and host bacterial cell. Prophage can exist in a cell for a long period suggests a similar possible mechanism for the viral origin of cancer. It provides a way to study the gene linkage.

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