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CBG Bacteria HELEP > CBG Lecture 19: Bacterial Transduction > Flashcards

CBG Lecture 19: Bacterial Transduction Flashcards

1
Q

define bacteriophage

A

a virus that infects bacteria

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2
Q

define lysogenic cycle

A

phage integrates into chromosome and is replicated along with the bacterial DNA

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3
Q

define lytic cyccle

A

the phage replicates in the host cell, releasing a new gen of viruses when the infected cell lyses

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4
Q

define virulent phage

A

reproduces only through lytic cycle

kills host

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5
Q

define prophage

A

a temperate bacteriophage integrated into the chromosome of the host bacterium

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6
Q

define temperate phage

A

can use lytic or lysogenic cycle

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7
Q

define plaque

A

a clear patch on bacterial lawn showing where cells have been lysed by phage infection

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8
Q

what two phages did Hershey and Rotman use

A

h-r+ and h+r-

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9
Q

wgucg E.coli strains can h- infect

A

E.coli strains B and B/2

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10
Q

which phage can infect E.coli B and B/2

A

h-

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11
Q

what happens when h- infects E.coli strains B and B/2

A

clear

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12
Q

which strain can h+ infect

A

strain B E.coli

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13
Q

what infects strain B E.coli

A

h+ and h=

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14
Q

what happens when h+ infects strain B

A

cloudy plaques

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15
Q

which infection gives clear plate

A

when h- infects E.coli strains B and B/2

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16
Q

which infection gives cloudy plaque

A

when h+ infects strain B

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17
Q

what does r- do

A

lyses cells rapidly giving large plaques

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18
Q

what does r+ do

A

lyses cells slowly giving small plaques

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19
Q

how are large plaques formed

A

by r- lysing cells rapidly

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20
Q

how are small plaques formed

A

by r+ lysing cells slowly

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21
Q

why do you cross h-r+ with h+r- in B strain bacteria

A

because this is the only strain which both phages can infect

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22
Q

why is high concn of phage used

A

to ensure multiple infections occur

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23
Q

when experimenting with phages, how do you ensure multiple infections occur

A

high concn of phage use

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24
Q

what is genotype of clear and small

A

h- r+

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25
Q

what is genotype of clear and large

A

h- r-

26
Q

what is genotype of cloudy and small

A

h+ r+

27
Q

what is genotype of cloudy and large

A

h+ r-

28
Q

what is phenotype of h- r+

A

clear and small

29
Q

what is phenotype of h+ r+

A

cloudy and small

30
Q

what is phenotype of h+ r-

A

cloudy and large

31
Q

what is phenotype of h-r-

A

clear and large

32
Q

what causes triggering of lytic from lysogenic cycle

A

stressors

eg. UV - excises the phage DNA

33
Q

what do plaques show

A

where cells have been lysed

34
Q

what types of transduction are there

A

generalised

specific

35
Q

what is generalised transduction

A

phages carry any part of the bacterial chromosomes

36
Q

what can cotransduction be useful for

A

mapping genes (like cotransformation) - a headful of DNA is transferred at a time

37
Q

what type of transduction where phages carry any part of the bact chromosome

A

generalised

38
Q

what is specialisd transduction

A

phages carry only restricted parts of the bacterial chromosome

39
Q

compare specialised transduction to generalized

A

in generalised phages carry ANY part of bact chrom and it involves the lytic cycle but in specialised transduction the lysogenic cycle is involved and specific genes are transferred - those next to phage attachment sites

40
Q

give example of a phage used in specialised transduction

A

lamda phage

41
Q

how can phages be excised from bact chrom

A

production of initial lysate then rare abnormal outlooping

42
Q

which genes are transferred in specialised transduction

A

those next to phage attachment sites

43
Q

what can transfer of genes be via

A

lysogenic incorporation into the bacterial chromosome or by recombination

44
Q

what are the two ways that excision can appear

A

production of initial lysate

transduction by initial lysate

45
Q

what is a bacterial lawn

A

the field of bacteria formed when all the individual colonies on a petri dish agar plate merge

46
Q

what did hershey and rotman do

A

h-r+ and h+r- crossing to map phage genes

47
Q

what did Lederberg and zinder do

A

can recombination occur in salmonella as it does in E.coli

48
Q

what is production of initial lysate

A

produced via outlooping - involved in the excision of phage from bacterial chrom

49
Q

what is transduction of initial lysate involved in

A

new genetic material in recipient cell

50
Q

name some phages that show generalised transduction

A

p1 and p22

51
Q

where does lamda phage insert betwen

A

specialised transducer which inserts between the gal and bio genes in the E.coli host chrom

52
Q

how does lamda phage excise out of bact chrom

A

lamda phage is a specialised transducer and normally excises out of bact chrom via an outlooping mechanism that is precisely the reverse of its integration

53
Q

when can lamda phage transduce

A

only when an occasional faulty outlooping includes the gal or bio genes into the phage cycle

54
Q

what is a lysate

A

A popn of progeny phages

55
Q

what is a known temperate phage of salmonella

A

P22 - it fits in the filter of U tube

56
Q

what is zygotic induction

A

The sudden release of a lysogenic phage from an Hfr chromosome when the prophage enters the F− cell, and the subsequent lysis of the recipient cell.

57
Q

how is the prophage attached to the bacterial genome

A

reciprocal recombination of lamda phage into E.coli chromsome = takes place between a specific attachement site of the circular lamda DNA and specific region on bac chrom between the gal and bio genes

58
Q

what can specialised transduction prodeuce

A

normal labda, or abnormal lamda d gal - the transducing particle

59
Q

when does transduction occur

A

when newly forming phages acquire host genes and transfer them to other bacterial cells

60
Q

what is specialised transduction due to

A

faulty separation of the prophage from the bacterial chrom so the new phage includes both phage and bacterial genes = the transducing phage can transfer only specific host genes

CBG Bacteria HELEP (3 decks)

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