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GENETIC TRANSFER AND RECOMBINATION   Genetic recombination refers to the exchange of genes between two DNA molecules to form new  combinations of genes on a chromosome. Genetic recombination regularly occurs as a part of  sexual reproduction. It contributes to genetic diversity of a population.  Vertical gene transfer--genes are passed from an organism to its offspring--in humans, that would  mean from parent to child--this also occurs in bacteria Horizontal gene transfer--genes are passed between two organisms in the same generation-- bacteria can do this in addition to vertical gene transfer (most other living things can't) Although bacteria do not undergo sexual reproduction, genetic recombination may occur in  several ways. In all mechanisms, the transfer of genetic material involves a donor cell that gives  DNA to a recipient cell. No matter how the DNA enters the recipient cell, this what occurs:
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Unformatted text preview: The recipient cell is now called a recombinant cell. TRANPOSONS These are small segments of DNA that can move from one region of a DNA molecule to another. They may move from one site to another on the same chromosome, or to another chromosome or a plasmid. Transposition is relatively rare, but it does occur in all organisms. Simple transposons are also called insertion sequences. They contain only: • A gene that codes for the enzyme transposase, which catalyzes cutting and resealing DNA • Recognition sites--short inverted repeat sequences of DNA that the enzyme recognizes as recombination sites between the transposon and the chromosome More complex transposons may carry additional genes not connected with the process of transposition. In bacteria, these may contain genes for antibiotic resistance of production of toxins. Plasmids may be made up of a collection of transposons....
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