BSC 310 Lecture Notes - Lecture 19: Hfr Cell, Chromosome, Calcium Chloride
Bacterial Recombinations
Three types of bacterial recombination result in a change in the DNA of recipient organisms.
The proteins expressed by the new genes lead to new physiological characteristics in the
bacteria.
Bacterial conjugation. Bacterial conjugation was first postulated in the 1940s by
Joshua Lederberg and Edward Tatum. The essential feature of the process is that two
bacterial cells come together and mate such that a gene transfer occurs between them.
One cell, the donor cell (F+), gives up DNA; and another cell, the recipient cell (F−),
receives the DNA. The transfer is nonreciprocal, and a special pilus called the sex
pilusjoins the donor and recipient during the transfer. The DNA most often transferred is
a copy of the F factor plasmid. The factor moves to the recipient, and when it enters the
recipient, it is copied to produce a double-stranded DNA for integration. The channel for
transfer is usually a special conjugation tube formed during contact between the two
cells (Figure 1 ).
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Figure 1
The process of bacterial conjugation using the F factor plasmid.
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Document Summary
Three types of bacterial recombination result in a change in the dna of recipient organisms. The proteins expressed by the new genes lead to new physiological characteristics in the bacteria. Bacterial conjugation was first postulated in the 1940s by. The essential feature of the process is that two bacterial cells come together and mate such that a gene transfer occurs between them. One cell, the donor cell (f+), gives up dna; and another cell, the recipient cell (f "), receives the dna. The transfer is nonreciprocal, and a special pilus called the sex pilusjoins the donor and recipient during the transfer. The dna most often transferred is a copy of the f factor plasmid. The factor moves to the recipient, and when it enters the recipient, it is copied to produce a double-stranded dna for integration. The channel for transfer is usually a special conjugation tube formed during contact between the two cells (figure 1 ).
