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POD Exam 1 > Phage and Genetic Exchange > Flashcards

Phage and Genetic Exchange Flashcards

1
Q

bacteriophage

A

viruses that infect bacteria

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2
Q

what genetic material can a bateriophage has

A

RNA and DNA

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3
Q

how do bacteriophage invade bacteria

A

tail fiber attach to surface

DNA is injected into the cell

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4
Q

how does filamentous phage invade bacteria

A

ingested by bacterium as a whole

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5
Q

what determines hosts specificity of bacteraphage

A

tail fiber proteins and host receptors

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6
Q

what happens to a phage after it has infected a bactrium

A

enters lytic or lysogenic life cycle

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7
Q

what happens in lytic cycle

A

phage replicates it DNA

lyses bacteria

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8
Q

name 2 processes that occur in lysogenic cycle

A

prophage

phage induction

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9
Q

prophage

A

DNA is integrated into bacterial chromosome or plasmid

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10
Q

phage induction

A

prophage an excise itself from the host DNA and start lytic cycle to multiply and release from bacteria.

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11
Q

name three types of bacteriaphages

A

virulent
temperate
filamentous

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12
Q

virulent bacteraphage does not have what

A

lysogenic cycle

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13
Q

temperate bacteraphage have what

A

either lytic or lysogenic cycle

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14
Q

filamentous phages do what to bacteria

A

no lyse of bacteria

continuously secrete new phages

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15
Q

what are 2 events in the lytic cycle

A

phage DNA replication

packaging

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16
Q

replicative form in lytic cycle

A

double stranded circular DNA

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17
Q

pac site in lytic cycle

A

phage coat proteins bind to specific DNA sequence

-packs DNA into an intact new phage

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18
Q

lambda phage replication replicates what

A

lambda phage genome that is linear dsDNA

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19
Q

cos sites

A

cohesive ends of lambda phage genome

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20
Q

what happens when lambda is injected into cell

A

cos site join to form circle

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21
Q

what types of replications are seen in lambda phage

A

0 replication

rolling circle replication

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22
Q

for lambda genome what is cancatermers? what process makes it?

A

tandem repeats

rolling circle replicatoin

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23
Q

for linear dsDNA, characteristic of ends that isn’t lamdba phage

A

blunt end without sticky cos sites

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24
Q

for linear dsDNA, what is stage 1

A

replication of multiple origins

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25
Q

for linear dsDNA, what is stage 2

A

replication following recombination

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26
Q

how are cancatermers formed in linear dsDNA,

A

recombination at ends of daughter DNA

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27
Q

what type of packaging does linear dsDNA have

A

headfull packaging

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28
Q

what is headfull packagin

A

phage head is filled with DNA until it is full

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29
Q

phages using headful packaging are more likely to

A

pack host bacterial chromosome DNA for genetic exchange

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30
Q

lysogen

A

bacterium that harbors a prophage

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31
Q

for temperate phage, what determines whether it goes into lytic cycle or lysogenic cycle

A

balance between CII synthesis (lysogeny) and gene products for DNA (lytic cycle)

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32
Q

what are 3 genes important for the lysogenic swtich

A

CI, CII, CIII

33
Q

what is the CI gene

A

“master switch” of lysogeny

34
Q

in early infection of bacteria what genes get infected

A

both CII and CIII

35
Q

what does CII do

A

activates expression of CI

36
Q

What does CIII do

A

prevent degradation of II

37
Q

what 2 domains does CI contiain

A

dimerization domain

DNA binding domain

38
Q

what are 2 functions of CI

A

transcriptional repressor for lytic cycle

transcription activator- its own expression

39
Q

how does phage DNA integrate into the host chromosome

A

site specific DNA recombination b/w phage attachment site (attP) and bacterial attachment site (attB)

40
Q

the recombination between phage attachment site (attP) and bacterial attachment site (attB) is mediated by who

A

phage integase

41
Q

lysogeny (lysogenic cylce) is maintained by what

A

CI dimmers

42
Q

When DNA gets damaged with phage inside DNA what happens

A
  • ssDNA produced
  • ssDNA binds RecA
  • -then RecA binds CI
  • CI leaves DNA
43
Q

When CI autocleaves form DNA what genes are de-represse

A

cro
integrase
excisase

44
Q

what does cro gene do

A

inihibit further expression of CI

45
Q

integrase and excisase form what

A

site-specific recombinase complex

46
Q

recombinase complex does what

A

recognizes hybrid attachment sites and excises the prophage from host chromosome by site specific recombination
-DNA becomes ciruclar

47
Q

what is genetic exchange

A

genetic exchange between 2 bacterial cells

48
Q

name 3 mechanisms for genetic exchange

A

transduction
conjugation
transformation

49
Q

define transduction

A

transferring DNA from a donor cell to a recipient cell by bacteriophage

50
Q

what are two types of tansduction

A

generalized

speacilized

51
Q

what makes a phage a transducing phage

A
  1. package host DNA

2. low sequence or no sequence specificity requirement for packing DNA into head

52
Q

What is generalized transduction

A

phage infect bacterium
host DNA fragmented
phage DNA made with 1% host DNA fragment in it

53
Q

Specialized transduction

A

induction of prophage from lysogency

  • takes places b/w host and bacterial DNA
  • new phage have piece of host DNA
  • usually host DNA that is close to attachment site gets mixed in
54
Q

conjugation

A

transfer of DNA from a donor cell to a recipient cell by plasmid

55
Q

conjugation requires what

A

cell-cell contact initiated by sex/F pilus

56
Q

what is a plasmid

A

circular dsDNA exists in bacterium independent of chromosome

57
Q

self-transmisssible plasmids also called what? and characterstic

A

F factor/plasmid

have all the genes needed for moving among cells

58
Q

mobolize plasmids

A

have some but not all the genes for transmission, need F plasmid for help

59
Q

what is sex/F pilus

A

bacteria containing an F plasmid have a hair life appendage on their surface

60
Q

what does F pilus initiate

A

cell-cell contact b/w donor and recipient cells during conjugation

61
Q

F + bacteria or male bacteria

A

bacteria with an F plasmid

donors of DNA conjugation

62
Q

F- bacteria

A

no sex pilus

recipients during conjugation

63
Q

steps for DNA transfer during conjugation

A
  1. nick DNA by endonucleuase
  2. unwind helicase and transfer
  3. synthesis of DNA in new strand
64
Q

Steps for cell connection for conjugation

A

mating bridge

65
Q

what initiates the transfer of DNA in conjugation

A

a cut at OriT - origin of transfer on plasmid

66
Q

in conjugation , in what direction is DNA transferred

A

5’ to 3’

67
Q

tranconjugate

A

the call that has received a transferred F plasmid in conjugation

68
Q

what is high-frequency recombinant strains or Hfr

A

integrated with chromosome F plasmid

69
Q

Where does F plasmid exist as an episome

A

outside the chromosome

70
Q

why does a Hfr strain cause high frequency of recombinant strain?

A
  1. chromosome DNA of Hfr bacteria can be trasnferred to recipient strain
  2. integrated F plasmid can be released from chromosoe and take some chromosome DNA with it
71
Q

how is Hfr stain trasnfere

A
  1. transfer unidirectional from 5’ to 3’

2. genes closer to oriT transfer first

72
Q

what does R plasmid carry

A

multiple antibiotic resistance genes

73
Q

how does R plasmid acquire antibiotic genes

A

transposon-mediated recombination

74
Q

MRSA (methicillin resistant S. aurea) , scary!

A

resistant to virtually at bacteria

vancomycin- only one not resistant

75
Q

is vancomycin resistance common

A

yes

76
Q

Transformation

A

uptake of naked DNA by bacterial cell

77
Q

tranfection

A

Eukaryotic cells take up of naked DNA

78
Q

competence

A

ability of bacteria to take up naked DNA

79
Q

competence pheromes

A

signal cells to become competent

POD Exam 1 (17 decks)

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