Microbiology Procedure

Index >> Bacterial Recombination >> Chromosome Transfer

Chromosome Transfer

	Chromosome Transfer Transfer of the bacterial chromosome from donor to recipient cell is controlled by the sex factor, which is integrated in the chromosome. The origin of the transfer is located within the factor. The sex factor breaks at the origin, and the chromosome is transferred as a ) linear structure. The origin and the part of the sex factor behind it is transferred first. The rest of the factor is transferred at the tail of the chromosome. One chromosome remains in the donor, while the other is transferred to the recipient, which gains two preexisting strands
In the second class of models it is supposed that transfer and replication take place simultaneously in the donor cell. (B) In the original form of this model it was postulated that a chromosome copy was transferred into the recipient cell as it was being synthesized. The recipient cell received one pre-existing strand and one newly synthesized strand. (C) According to a later version of the model it was suggested that only one strand of the DNA chromosome is freed by replication for passage into the recipient cell
There is transfer of only one pre-existing strand. This model is the rolling circle model or Gilbert and Dressler(1968).Experiments with radioactive isotopes clearly refuted the idea of the first model (that there is transfer of a pre-existing duplex). The experiments demonstrated that only one of the two previously existing parental donor strands is transferred to the recipient cell. Radioactive labelling data are consistent with the second and the third models born of which require DNA synthesis in the donor, Genetic and biochemical analyses show that only one strand of the donor chromosome is transferred to the recipient cell, and, therefore, support the rolling circle mode1. Plasmid transfer takes place

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