Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 3155 > Chapter 8 > Flashcards

Chapter 8 Flashcards

Bacteriophage Lambda

1
Q

a general profile of bacteriophage Lambda

A

linear dsDNA, 40-60kb, ds-DNA with ss-DNA ends (cos), transcriptional regulation of gene expression (immediate early, early, late genes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what happens when the genome is injected to the cell?

A

DNA circularizes upon entry via cohesive ends.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

infection of E.coli by phage lambda can have two possible outcomes:

A

the lytic growth cycle or prophage state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

phages can either:

A

grow lytically or exist as a repressed prophage are called temperate phages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

phage adsorption and DNA entry depends on

A

cellular proteins involved in sugar transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

at the tip of the tail is a [ ] protein that binds to an E.coli outer membrane protein, [ ]

A

J and LamB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

injection of DNA through the tail and into the cell requires

A

the cytoplasmic membrane components of mannose permease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

transcription by host RNA polymerase then begins at two promoters, P[L] and P[R], located on

A

either side of the repressor gene, cI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

the lambda lytic transcription by

A

termination and antitermination of RNA synthesis at specific sites on the genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

transcripts from P[L] and P[R] expresses

A

the N and cro genes; these “immediate-early” transcripts end at transcription terminators t[L]1 and t[R]1.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

N protein is a transcriptional antiterminator that

A

modifies RNA polymerase so that transcripts initiated at P[L] and P[R] are no longer terminated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

For N to function, it binds to

A

specific mRNA sequences, called NUT sequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

antitermination of t[L]1 extend P[L] through

A

the recombinase genes gam, bet, and exo, the site-specific recombination genes xis and int across the locus for site-specific recombination, attP, all the way to Ea47

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Q is

A

a transcriptional antiterminator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

P[R]’ transcript constitutively expresses a short transcript that ends at

A

t[R]’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Q antiterminates P[R]’ transcript, leading to

A

production of a very long “late” gene transcript of the cell lysis, head, tail, and tail fiber assembly genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the CI repressor blocks expression of the lytic program by

A

regulating three nearby promoters: P[L], P[R], P[RM]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

when lambda infects active cells in logarithmic growth, the phage grows

A

lytically in most of the cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

when lambda infects metabolically sluggish, stationary phage cells, most of the infected cells are

A

lysogenized. the CI protein produced to shut down transcription of the lytic genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

three repressor-binding sites, called operators, overlap

A

the P[L] and P[R] promoters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

CI binds to the operators as a dimer with the following affinities:

A

O[R]1>O[R]2=O[R]3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

a second promoter, called P[RM] for repressor maintenance, is located near

A

P[R] but initates transcription in the opposite direction; this promoter directs transcription of cI mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

P[RM] is a weak promoter, but in a prophage, P[RM] is activated to produce

A

sufficient CI repressor to shut down P[R] and P[L]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

CI bound to O[R]2 is physically near P[RM] and forms favourable contacts with

A

RNA polymerase; making P[RM] a better promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

when the CI concentration is too high,

A

O[R]3 is also occupied and transcription from P[RM] is turned off until the CI concentration returns to a normal level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Cleavage of CI repressor in cells with damaged DNA leads to

A

prophage induction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

induction occurs in cells that have a DNA damage caused by

A

UV light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

when damaged nucleotides are removed by

A

excision repair system of SOS genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

the SOS genes of undamaged cells are repressed by

A

the cellular LexA repressor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

excision repair excise ss-DNA oligonucleotides, which in turn bind to and activate

A

the cell’s RecA recombination protein such that it acquires a “coprotease” activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

the LexA repressor has a weak autoprotease activity that is enhanced by

A

binding to the activated RecA protein, with the result that the LexA repressor cleaves itself into two domains and loses repressor activity, allowing induction of SOS gene transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

CI’s weak autoprotease activity is stimulated by

A

activated RecA, leading to linker cleavage that inactivates CI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Inactivation of CI leads to

A

transcripiton from P[R] and P[L]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

N-antiterminated transcription leads to expression of both

A

Xis and Int, which in turn sponsor excision of the prophage DNA from the bacterial chromosome, and the lytic transcription pattern ensues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

the Cro repressor suppresses

A

CI synthesis and regulates early gene transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

the dimeric Cro protein is the repressor that

A

establishes and controls a lytic infection by turning off the synthesis of CI.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Cro binds to the same operators as CI repressor, but with different affinities

A

O[R]3>O[R]2=O[R]1

38
Q

early during lytic growth, either during an infection or induction of a lysogen, Cro binds to

A

O[R]3 and blocks P[RM]

39
Q

Binding to O[R]3 and blocking P[RM] prevents

A

CI expression and channels the infected cell to lytic growth.

40
Q

later during lytic growth, sufficient Cro accumulation fills

A

O[R]2 and O[R]1, repressing P[R] and P[L], reducing synthesis of early proteins

41
Q

Sufficient CI ensures that

A

P[R] and P[L] are turned off and P[RM] is turned on

42
Q

Insufficient CI results in

A

the lytic program

43
Q

the amount of CI produced from P[RE] depends in

A

turn on the level of the P[RE] activator protein, CII

44
Q

the cII gene is located just downstream from

A

cro

45
Q

the cII gene is transcribed from

A

P[R] promoter and sponsored by N antitermination

46
Q

P[RE], like P[RM] is a weak promoter that is activated by

A

CII

47
Q

since the level of CI produced from P[RE] depends on the level of CII, the lysis/lysogeny decision depends on

A

the intracellular concentration of CII protein

48
Q

CII activates two additonal promoters:

A

P[int] and P[AQ]

49
Q

P[int] is

A

a CII-dependent promoter for encoding Int, the site-specific recombinase that inserts the lambda prophage into the bacterial chromosome

50
Q

P[AQ] for

A

encoding an antisense transcript of Q that lowers Q expression, delaying the late gene expression

51
Q

the level of CII is determined with inactivation by

A

host cell proteases and lower stability in metabolically active cells than in inactive cells and higher stability by CIII

52
Q

CIII is for

A

inhibiting the host proteases

53
Q

Int is a phage protein that

A

catalyzes crossing-over between the phage attP site, near the int gene, and the bacterial attB site, located between the gal and bio operons

54
Q

attP is deisgnated

A

POP’ to symbolize its three parts, where O being core squence that is found in both attP and attB

55
Q

Int binds to two different DNA sequence motifs within

A

the arms and the core of attP

56
Q

Int binds strongly to

A

the arm sequence that has binding sites for the E.coli DNA bending protein, IHF

57
Q

IHF is for

A

bending the arms to allow Int to make bridging-contacts with the core sequences

58
Q

an intasome is

A

a complex nucleoprotein structure

59
Q

three proteins that are involved in the reverse reaction to generate a circular DNA molecule from the integrated lambda phage are

A

Int, IHF, Xis

60
Q

the attP-attB exchange during integration shuffles the att sequences, creating

A

attL (BOP’) and attR (POB’) sites at the left and right junctions between the prophage DNA and the bacterial chromosome

61
Q

When an integrated prophage is induced, N-antiterminated mRNA from PL produces

A

Int and Xis

62
Q

lambda DNA replication is directed by

A

O and P, but carried out by host cell proteins

63
Q

Expression of the early genes O and P leads to

A

lambda DNA replication

64
Q

The O protein binds to

A

multiple sites in the replication origin, ori lambda, forming a nuceloprotein structure, the O-some

65
Q

Forming the O-some, the two strands of an adjacent AT-rich segment of the DNA become

A

unpaired

66
Q

the P protein recruits

A

the E.coli replication Helicase DnaB to the O-some

67
Q

In hijacking DnaB, P binds so tightly that

A

E.coli chaperone proteins DnaJ and DnaK are needed to release it from the O-some

68
Q

Growing points for DNA replication are set up using

A

E.coli replication proteins

69
Q

RNA primers are laid down on the separated DNA strands, and DNA polymerase extends

A

these primers to begin copying the DNA

70
Q

Bidirectional replication produces

A

progeny circles at early times, prior to the lysis/lysogeny decision

71
Q

during lytic growth, there is a shift to

A

rolling circle replication

72
Q

rolling circle replication produces

A

multimeric ds-DNAs, called concatemers, which are the DNA packing substrate

73
Q

assembly of lambda heads involves

A

chaperones and scaffolding proteins

74
Q

DNA is inserted into performed proheads by

A

an ATP-dependent mechanism

75
Q

Concatemeric lambda DNA generated by rolling circle replication is cut

A

to generate unit-length virion DNA molecules during packing of the DNA into the proheads shell

76
Q

cutting requires the introduction of nicks, staggered

A

12 bp apart, so that the ss-cos ends are made

77
Q

terminase is

A

the viral cutting enzyme containing Nu1 and A subunits

78
Q

Nu1 binds to

A

an anchoring site cosB

79
Q

protein A cleaves

A

the DNA at an adjacent nicking site, cosN

80
Q

following nicking of a concatemer, terminase separates

A

the cohesive ends, remaining bound to the end of the DNA at cosB

81
Q

DNA-protein complex docks at

A

the portal vertex of a proheads, and DNA packing proceeds

82
Q

translocation of the DNA into the proheads is powered by

A

ATP hydrolysis

83
Q

during translocation of the DNA into the proheads, the E shell subunits undergo

A

rearrangement, causing the shell to expand and become more angular

84
Q

As the shell is filled, the next cos site of the concatemer approaches

A

the terminase located at the portal

85
Q

cutting the second cos sequence requires

A

recognition of cosQ, a site located just upstream of the nicking site cosN, and this completes packing of a chromosome

86
Q

terminase undocks from the filled head, remaining bound to

A

the end of the concatemer to form a new complex that is ready to bind to another proheads

87
Q

at the end of lytic growth, the host cell is

A

lysed to release progeny phages

88
Q

two lambda gene products govern peptidoglycan hydrolysis:

A

protein R and S

89
Q

Protein R attacks

A

the cell’s peptidoglycan layer

90
Q

Protein S provides

A

a route through the cytoplasmic membrane for R

91
Q

Protein Rz and Rz1 are required for

A

lysis of cells in the presence of high concentration of divalent cations

BIOL 3155 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions