  UAA !
UAG ( ! Bernstein( "!
UGA

1

T4  T4     169K

2

Photograph of phage T2
plaques on a lawn of E. coli
bacteria

T2 phage    

T2 r : rapid-lysis mutant
T2 r+:wild-type
T2 mutant phage

3

Phage recombination in cells infectedwith two different strains of phage T2
T2h:T2# %
&# *
T2 r : rapid-lysis B/2B$5/3'#012-+)"*!$#
h+r+, hr, hr+, h+r+1945 4/,2.
#'( '4

The life cycle of a lysogenic bacterial virus  ⇨λ  ⇨  λ    48K

5

Insertion of thechromosome of phage
λ into E.coli
chromosome

6Insertion of Mu DNA

Muλ#  !" Mu ## 7

Transduction, the passive transfer of genetic material
from one bacterium to another by means of carrier
phage particles

P1  P1  

93Kbp 2.28

Specialized
transducing phage

9

The demonstrationof crossing over within the gene10

The genetic map of the rIIA and rIIB genes of phage T4

11S. Benzer, PNAS, (1961)

" ' %  !# %
($&!% 

Deletion mutations with in the rII region of T4

12

The rII region
consists of two
distinct genes thatcan complement
each other during
simultaneous
infection- 

13

The Genetic Systems Provided by E.
coli
Molecular Biology of the Gene

14

Fluctuation analysis of bacterial resistance to phage() 

15  

Replica plating16

Isolation of mutant E. coli
cells with a specific growthfactor requirement   (auxotroph) (prototroph)(!#"")



17

Enriching mutants I
direct selection

counterselection



18

Enriching mutants IIpH-sensitive dyes todetect metabolic mutants

Brute force isolation
physical selection    

19

The use of growth factor requirments to demonstratesexuality in E. coli

J. Lederberg & Tatum (1946)  

20

The attachment ofa male F pilus to
the surface of a femail cell

Type-I pili

F pilus21 DsRed Ex- press  
Alexa-488 R17

22



23

Hfr : the positions whereinsertion elements on F
recombine with the bacterial
chromosome

fin : fertility inhibitionphi : phage inhibition

The genetic map of F
factor of E. coli
(94 kb)inc : incompatibility
rep : replication
tra : the transfer of the F factor to female cells
ilz : immunity to lethal zygosis
ori : origin of transer replication

24

The transfer of F+ DNA
to an F- cell



25

Hfr (high frequency of recombination)

Movement of the bacterial
chromosome from an Hfr cell
into an F- cell

Integratiion of the F factor into
the main chromosome

26

Conjugation between F- and Hfr bacteria, as
shown in a classic diagram

27

F. Jacob & E.L. Wollman, Sexality and the Genetics of Bacteria, (1961)

The frequency fo donor Hfr marker genes
The relative gene order ⇨ azi-T1-lac-gal

28Order of genes in conjugal transfer
in different Hfr strains

29Complete genetic map of E. coli I
Flagellar region II

Flagellar region III

Flagellar region Igal

thrleuazilac30

Complete genetic map of E. coli II31

The genetic maps


4.6Mb


4.2Mb32
INAGJCAL0*+'4=KELAGJCAL)+1$-OM 1NTs)+/;1$-O M 2NE@DH?F<LB,$851"098(". %+/1ONM 3NIIN1!OM 4N

F<>I,&7

2F<>I

2.14 058(10:8+#87-!63&