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Unformatted text preview: 10/6/2010 1 Chapter 27 Prokaryote structure & function Conjugation & Plasmids • Genetic material is transferred between two bacteria that are temporarily joined Sounds like sex! • F factor (fertility) a plasmid of 25 genes that confers ability to produce sex pili in the donor cell “mating bridge” Fig. 27-12 Sex pilus 1 μm Conjugation and Recombination in Eschericia coli • Two cases: Conjugation & transfer of an F-plasmid F+ and F- cells: form mating bridge: both cells become F+ Conjugation & transfer of an Hfr bacterial chromosome Hfr & F- cell: new combination of genes but no F factor. Both cells are F- 10/6/2010 2 Fig. 27-13 F plasmid F + cel F – cel Mating bridge Bacterial chromosome Bacterial chromosome (a) Conjugation and transfer of an F plasmid F + cel F + cel F – cel (b) Conjugation and transfer of part of an Hfr bacterial chromosome F factor Hfr cel A + A + A + A + A + A – A – A – A – A + Recombinant F – bacterium R plasmids • Carry genes, “resistance genes” that confer antibiotic resistance on recipient bacterial cell • R plasmids encode for genes that destroy or hinder the effectiveness of antibiotics such as & streptomycin Why are these antibiotic effective? Against what? Nutritional diversity and metabolic adaptations of prokaryotes is most remarkable They are the foundation of the major reasons I gave at the beginning of todays’ lecture of why we study prokaryotes Q: How do bacteria & archaea make a living?...
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This note was uploaded on 02/06/2011 for the course BIO 120 at USC.