Overview Transformation the uptake of naked DNA from the environment any DNA can be used only bacteria that are "competent" are able to undergo transformation competence factor released by stressed bacteria induces this unique ability a feature of many bacteria especially S. pneumoniae, H. influenzae type B, Neisseria ("SHiN") "having naked SHiNs was a transforming experience" Conjugation "bacterial sex" the major mechanism by which bacteria exchange plasmids allows the transmission of resistance to drugs F plasmid contains the genes required for conjugation F+ bacteria have the plasmid F- bacteria do not Hfr ("high frequency") bacteria have incorporated the F plasmid into their chromosomal DNA F+ x F- plasmid is replicated inside F+ cell plasmid is transferred through pilus from F+ cell to F- cell only plasmid itself is transferred no transfer of chromosomal genes Hfr x F- plasmid and some flanking chromosomal DNA is replicated inside Hfr cell plasmid and some chromsomal DNA is transferred through pilus from F+ cell to F- cell in this case, both plasmid itself and chromosomal genes are transferred "a conjugal visit" Transduction transfer of bacterial DNA using virus (phage) as a carrier generalized transduction ("packaging") lytic phage phage cleaves bacterial DNA parts of bacterial chromosomal DNA may become packaged in viral capsid DNA then travels in phage to infect another bacterium, transferring genes specialized ("excision") lysogenic phage phage incorporates viral DNA into bacterial chromosome when phage DNA is excised from the bacterial chromosome, flanking bacterial genes may be excised with it DNA then travels in phage to infect another bacterium, transferring genes toxin genes encoded in a lysogenic phage shiga-like botulinum cholera diphtheria erythrogenic toxin of S. pyogenes Transposition transposons (also known as insertion elements or transposable elements) are segments of DNA that can move from one location to another allows transfer of genes from plasmid to chromosome and vice-versa removal of a plasmid from the chromosomal DNA may include some flanking chromosomal DNA that may be transferred to another bacterium along with the plasmid