PRESENTED BY :- KIRANB.S.c. BIOTECH 4TH SEM

TRANSDUCTION AND TRANSFECTION

TRANSDUCTION

Transduction is the process by which DNA is transferred from one bacterium to another by a virus.

It also refers to the process whereby foreign DNA is introduced into another cell via a viral vector.

Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA (which occurs in conjugation), and it is DNase resistant.

Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome.

LYTIC AND LYSOGENIC (TEMPERATE) CYCLES

Transduction happens through either the lytic cycle or the lysogenic cycle.

If the lysogenic cycle is adopted, the phage chromosome is integrated (by covalent bonds) into the bacterial chromosome, where it can remain dormant for thousands of generations.

If the lysogen is induced (by UV light for example), the phage genome is excised from the bacterial chromosome and initiates the lytic cycle, which culminates in lysis of the cell and the release of phage particles.

The lytic cycle leads to the production of new phage particles which are released by lysis of the host.

LYTIC AND LYSOGENIC CYCLE IN LAMBDA PHAGE

Generalized transduction :- Generalized transduction is the process by

which any bacterial gene may be transferred to another bacterium via a bacteriophage, and typically carries only bacterial DNA and no viral DNA. In essence, this is the packaging of bacterial DNA into a viral envelope.

Specialized transduction:- Specialized transduction is the process by

which a restricted set of bacterial genes is transferred to another bacterium.

The genes that get transferred (donor genes) depend on where the phage genome is located on the chromosome.

MEDICAL APPLICATIONS

Resistance to anti-biotic drugs Correcting genetic diseases by direct

modification of genetic errors

TRANSFECTION Transfection is the process

of deliberately introducing nucleic acids into cells.

Transfection of animal cells typically involves opening transient pores or "holes" in the cell membrane to allow the uptake of material.

It involves the use of physical and chemical methods to persuade cells to take up DNA into the cells.

There are different transfer methods like chemical transfection, liposome mediated transfection , lipofection , electroporation.

The direct physical introduction of DNA into the cells involves microinjection and particle bombardment.

LIPOFECTION Lipofection (or liposome transfection) is a technique used to inject genetic material into a cell by means of liposomes, which are vesicles that can easily merge with the cell membrane since they are both made of a phospholipid bilayer.

Lipofection generally uses a positively charged (cationic) lipid to form an aggregate with the negatively charged (anionic) genetic material.

A net positive charge on this aggregate has been assumed to increase the effectiveness of transfection through the negatively charged phospholipid bilayer.

The uptake of DNA through the process of endocytosis.

ELECTROPORATION

Electroporation is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, by inducing the formation of pores within a membrane and allowing chemicals, drugs, or DNA to be introduced into the cell.

PARTICLE BOMBARTMENT

Also known as microprojectile or biolistic method.

It employs foreign DNA coated with high velocity gold or tungsten particles to deliver DNA into target cells.

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