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POD Exam 1 > Phage and Genetic Exchange > Flashcards

Phage and Genetic Exchange Flashcards

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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
for linear dsDNA, what is stage 2
replication following recombination
26
how are cancatermers formed in linear dsDNA,
recombination at ends of daughter DNA
27
what type of packaging does linear dsDNA have
headfull packaging
28
what is headfull packagin
phage head is filled with DNA until it is full
29
phages using headful packaging are more likely to
pack host bacterial chromosome DNA for genetic exchange
30
lysogen
bacterium that harbors a prophage
31
for temperate phage, what determines whether it goes into lytic cycle or lysogenic cycle
balance between CII synthesis (lysogeny) and gene products for DNA (lytic cycle)
32
what are 3 genes important for the lysogenic swtich
CI, CII, CIII
33
what is the CI gene
"master switch" of lysogeny
34
in early infection of bacteria what genes get infected
both CII and CIII
35
what does CII do
activates expression of CI
36
What does CIII do
prevent degradation of II
37
what 2 domains does CI contiain
dimerization domain | DNA binding domain
38
what are 2 functions of CI
transcriptional repressor for lytic cycle | transcription activator- its own expression
39
how does phage DNA integrate into the host chromosome
site specific DNA recombination b/w phage attachment site (attP) and bacterial attachment site (attB)
40
the recombination between phage attachment site (attP) and bacterial attachment site (attB) is mediated by who
phage integase
41
lysogeny (lysogenic cylce) is maintained by what
CI dimmers
42
When DNA gets damaged with phage inside DNA what happens
- ssDNA produced - ssDNA binds RecA - -then RecA binds CI - CI leaves DNA
43
When CI autocleaves form DNA what genes are de-represse
cro integrase excisase
44
what does cro gene do
inihibit further expression of CI
45
integrase and excisase form what
site-specific recombinase complex
46
recombinase complex does what
recognizes hybrid attachment sites and excises the prophage from host chromosome by site specific recombination -DNA becomes ciruclar
47
what is genetic exchange
genetic exchange between 2 bacterial cells
48
name 3 mechanisms for genetic exchange
transduction conjugation transformation
49
define transduction
transferring DNA from a donor cell to a recipient cell by bacteriophage
50
what are two types of tansduction
generalized | speacilized
51
what makes a phage a transducing phage
1. package host DNA | 2. low sequence or no sequence specificity requirement for packing DNA into head
52
What is generalized transduction
phage infect bacterium host DNA fragmented phage DNA made with 1% host DNA fragment in it
53
Specialized transduction
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
conjugation
transfer of DNA from a donor cell to a recipient cell by plasmid
55
conjugation requires what
cell-cell contact initiated by sex/F pilus
56
what is a plasmid
circular dsDNA exists in bacterium independent of chromosome
57
self-transmisssible plasmids also called what? and characterstic
F factor/plasmid | have all the genes needed for moving among cells
58
mobolize plasmids
have some but not all the genes for transmission, need F plasmid for help
59
what is sex/F pilus
bacteria containing an F plasmid have a hair life appendage on their surface
60
what does F pilus initiate
cell-cell contact b/w donor and recipient cells during conjugation
61
F + bacteria or male bacteria
bacteria with an F plasmid | donors of DNA conjugation
62
F- bacteria
no sex pilus | recipients during conjugation
63
steps for DNA transfer during conjugation
1. nick DNA by endonucleuase 2. unwind helicase and transfer 3. synthesis of DNA in new strand
64
Steps for cell connection for conjugation
mating bridge
65
what initiates the transfer of DNA in conjugation
a cut at OriT - origin of transfer on plasmid
66
in conjugation , in what direction is DNA transferred
5' to 3'
67
tranconjugate
the call that has received a transferred F plasmid in conjugation
68
what is high-frequency recombinant strains or Hfr
integrated with chromosome F plasmid
69
Where does F plasmid exist as an episome
outside the chromosome
70
why does a Hfr strain cause high frequency of recombinant strain?
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
how is Hfr stain trasnfere
1. transfer unidirectional from 5' to 3' | 2. genes closer to oriT transfer first
72
what does R plasmid carry
multiple antibiotic resistance genes
73
how does R plasmid acquire antibiotic genes
transposon-mediated recombination
74
MRSA (methicillin resistant S. aurea) , scary!
resistant to virtually at bacteria | vancomycin- only one not resistant
75
is vancomycin resistance common
yes
76
Transformation
uptake of naked DNA by bacterial cell
77
tranfection
Eukaryotic cells take up of naked DNA
78
competence
ability of bacteria to take up naked DNA
79
competence pheromes
signal cells to become competent

POD Exam 1 (17 decks)

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