GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

19. BACTERIAL GENETICS: STABILITY, VARIATION, AND INHERITANCE

19.3. GENETIC TRANSFER AND RECOMBINATION

During Fertilization in eukaryotes, haploid Gene sets combine to form a diploid zygote. Following mitotic divisions and reduction division (Meiosis) in the resulting diploid Organism, Chromosomes from both parental sets are recombined, eventually giving rise to Cells with a haploid set of genes (Gametes) once again. This sexual method of genetic reshuffling is contrasted with parasexual processes, which include trait recombination in prokaryotes. Bacteria are almost exclusively haploid, possessing only a single set of genes. While bacteria do form zygotes, these are never the product of complete Cell Fusion. Typically, only a portion of the genetic material is transferred from a donor cell to a recipient cell, resulting in a partial zygote (merozygote). The recipient chromosome pairs with the donor chromosome fragment, and they exchange homologous segments. Upon subsequent Cell Division, a cell containing solely the recombinant chromosome is produced.

Three Mechanisms of Genetic transfer are known in bacteria: conjugation, Transduction, and transformation. Through these processes, DNA is transferred from a donor bacterium to a recipient bacterium. They differ fundamentally in the mode of DNA transport. Following DNA transfer, recombination takes place within the recipient cell, wherein the donor DNA is integrated into the recipient's genome. A cell that has undergone recombination is referred to as a recombinant (recombinant cell).