Genetic Recombination: Transformation

I. MICROBIAL GENETICS

G. Genetic Recombination in Bacteria

2. Transformation

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Genetic Recombination in Bacteria (def)

Genetic recombination is the transfer of DNA from one organism to another. The transferred donor DNA may then be integrated into the recipient's nucleoid by various mechanisms.

Natural mechanisms of genetic recombination in bacteria include:

a. transformation
b. transduction
c. conjungation

We will now look at transformation.

Transformation (def)

During transformation, DNAfragments (usually about 20 genes long) from a dead degraded bacterium bind to DNA binding proteins on the surface of a competent recipient bacterium. Nuclease enzymes then cut the bound DNA into fragments. One strand is destroyed and the other penetrates the recipient bacterium. This DNA fragment from the donor is then exchanged for a piece of the recipient's DNA by means of Rec A proteins (see Fig. 1 through 4).

GIF animation illustrating transformation in a competent bacterium.

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