LECTURE 9: GENETICS OF BACTERIA & THEIR VIRUSES II Fbacterial conjugation (rev) Fbacterial transformation Fbacteriophage genetics

BACTERIAL CONJUGATION Finterrupted-mating Fselective markers Fdonor is str s Frecipient is str r Forigin of replication transferred first F1 st transferred markers most frequent in exconjugants

BACTERIAL CONJUGATION Fbias in recovery of markers Fgradient of transfer used for determination of gene order only

Schaum’s Outlines – Genetics3 rd Ed., CH12, pp. 321 – th Ed., CH10, pp. 349 – 355

a)exogenote enters cell... merozygote = partial diploid b)single recombination event (3x, 5x,...) nonviable c)double recombination event (4x, 6x,...) viable BACTERIAL CONJUGATION

Fbias in recovery of markers Fgradient of transfer used for determination of gene order only F  to determine map distances, select late marker to ensure transfer of all relevant genes... high resolution mapping

BACTERIAL CONJUGATION Fhigh-resolution mapping by recombinant frequency

Schaum’s Outlines – Genetics3 rd Ed., CH12, pp. 321 – th Ed., CH10, pp. 349 – 355

TRANSFORMATION IN BACTERIA Fconversion of one genotype to another by uptake of exogenous DNA Ftransformation principle – demonstrated that DNA was responsible for inherited differences in polysaccharide character of S. pneumoniae (CH8)

TRANSFORMATION IN BACTERIA Fextracted DNA (in an experiment) breaks at random Fco-transformation of 2 tightly linked donor genes is more likely than 2 distant donor genes Fcells must be made competent to enable DNA entry Fdetergents Felectrical fields

TRANSFORMATION IN BACTERIA Fdependent on concentration of DNA in the medium

TRANSFORMATION IN BACTERIA FDNA must enter and recombine into the host

TRANSFORMATION IN BACTERIA Fpractice question, p. 237, #18

BACTERIOPHAGE GENETICS Fbacteriophage = eaters of bacteria FT-phages well studied; T-even and T-odd

BACTERIOPHAGE GENETICS Fbacteriophage = eaters of bacteria FT-phages well studied; T-even and T-odd

BACTERIOPHAGE GENETICS

Flysis = breaking of cell wall and release of phage particles Fbacteriophage lytic cycle...

BACTERIOPHAGE GENETICS Fphage plaques on a lawn of bacteria F1 plaque forming unit PFU = 1 phage particle Fplaque morphology Fhost range

BACTERIOPHAGE GENETICS Fphage cross: h – r + x h + r – F h + infect strain 1 F h – infect strains 1 & 2 F r + slow lysis, small plaques F r – slow lysis, large plaques

BACTERIOPHAGE GENETICS Flawn of 2 E. coli strains – 1 immune to h + phage

BACTERIOPHAGE GENETICS Fphage cross: h – r + x h + r – F h + clowdy F h – clear F r + small F r – large FRF = [ h + r + + h – r – ] TOTAL

TRANSDUCTION IN BACTERIA Falternative life cycles of temperate bacteriophage

TRANSDUCTION IN BACTERIA Fgeneralized transduction… random incorporation Flytic cycle, non-integrated phage

TRANSDUCTION IN BACTERIA Fco-transduction Fdonor leu + thr + azi r  recipient leu – thr – azi s thr leu azi

TRANSDUCTION IN BACTERIA Fgenetic map of the purB  cysB region in E. coli

TRANSDUCTION IN BACTERIA Fphage integration

TRANSDUCTION IN BACTERIA Fspecialized transduction… non- random incorporation Flysogenic cycle, integrated phage

TRANSDUCTION IN BACTERIA Fspecialized transduction… non- random incorporation Flysogenic cycle, integrated phage

TRANSDUCTION IN BACTERIA Ftransduction: phage acquire host genes and transfer them to other bacterial cells Fgeneralized transduction: transfers any host gene; and occurs when phage randomly package host DNA Fspecialized transduction: faulty separation of prophage (phage incorporated into host genome); new phage contains adjacent host genes only

GENETIC MAPS IN BACTERIA F E. coli linkage map (minutes)

GENETIC MAPS IN BACTERIA F5 minutes of the E. coli linkage map

GENETIC MAPS IN BACTERIA Fcorrelated genetic and physical maps in E. coli

SUMMARY: RECOMBINATION IN BACTERIA

BACTERIAL CONJUGATION AND RECOMBINATION MAPPING: PROBLEMS F in Griffiths chapter 5, beginning on page 179, add these questions to those listed at the end of lecture #8… #4, 14, 16-21, 24, 28 (eg. in class)-32 F begin with the solved problems on page 177 if you are having difficulty F look Schaum’s Outline (pp ) F try Schaum’s Outline questions 10.7 – 10.12