-
A lambda is..
A phage (virus) that infects E. Coli
-
what is the structure of the lambda phage from top to bottom?
- Head (Capsule) with DNA inside it
- Tail
- End Plate with connected
- Tail fibers
-
The genome of the phage DNA is a ________bp, ________-stranded, _______ DNA.
- 50,000 bp
- double-stranded
- circular DNA
-
What two life cycles can temperate phages follow?
- lysogenic cycle
- lytic cycle
-
what is a prophage?
phage DNA intergrated into the host genome
-
What are the steps of the lytic cycle?
- 1. Phage injects its DNA into cytoplasm
- 2. Phage DNA directs the synthesis of many new phages
- 3. Cell lyses and releases the new phages
- 4. New Phages can bind to bacterial cells
-
What are the steps of the lysogenic cycle?
- 1. Phage injects its DNA into cytoplasm
- 2. Phage DNA intergrates into host chromosome
- 3. Prophage DNA is copied when cell divides
- 4. On rare occasion, a prophage may be excised from host chromosome
-
Bacterial diseases are actually the result of...
lysogenic phage within the bacteria
-
Corynebacterium diphtheriae produces the toxin of...
diphtheria
-
Corynebacterium diphtheriae produces the toxin of diphtheria only when it is....
infected by the phage β.
-
Vibrio cholerae produces ...
cholera toxin
-
Vibrio cholerae produces cholera toxin, when it is....
infected with the phage CTXφ
-
Clostridium botulinum causes
botulism
-
Clostridium botulinum causes botulism; some
strains harbor the toxin genes on a.....
lysogenic phage
-
Streptococcus pyogenes causes...
scarlet fever
-
Streptococcus pyogenes causes scarlet fever toxin genes on...
phage T12.
-
Clostridium tetani causes....
tetanus
-
What are the four main section of the lambda genome arrangment?
- Lysogeny (recombination)
- Lysogeny
- Lysis
- Lytic (Coat protein)
-
What kind of genes are the early promoters and operators of the lambda phage genome?
lysogenic genes
-
What kind of genes is the att protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the int protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the xis protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the alpha protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the beta protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the gamma protein of the lambda phage genome?
lysogenic gene (recomb.)
-
What kind of genes is the clll prottein of the lambda phage genome?
lysogenic gene
-
What kind of genes is the N protein of the lambda phage genome?
lysogenic gene
-
What kind of genes is the cro protein of the lambda phage genome?
lysogenic gene
-
What kind of genes is the cll protein of the lambda phage genome?
lysogenic gene
-
What kind of genes is the Q protein of the lambda phage genome?
lytic gene (late regulator)
-
What kind of genes is the S protein of the lambda phage genome?
Lytic gene (lysis proteins)
-
What kind of genes is the R protein of the lambda phage genome?
lytic gene (lysis proteins)
-
What kind of genes is the cos protein of the lambda phage genome?
lytic gene (lysis protiens)
-
What kind of genes is the head gene of the lambda phage genome?
Lytic genes (coat proteins)
-
What kind of genes is the Tail genes of the lambda phage genome?
Lytic genes (Coat proteins)
-
what do PR and PL promoters express?
N and cro Genes only
-
What is the "Early" immediate early gene expression in the lytci cycle?
PR and PL promoters express N and cro genes.
-
the N protein in the lambda genome is an....
antiterminator protein
-
The N protein allows...
read through of early terminators to give delayed early gene expression
-
the Q protein in the lambda genome is an...
antiterminator protein
-
The Q protein allows...
PR' to read through to give late gene expression
-
N-mediated Antitermination allows ....
expression of Delayed Early Genes, including Q
-
Q-mediated Antitermination allows...
expression of Late Genes from PR’including phage proteins and lysis genes
-
the main three factor in the gene expression of the lytic cycle is...
- Immediate Early genes expressed from PR and PL yield Cro and N
- N-mediated Antitermination allows expression of Delayed Early Genes, including Q
- Q-mediated Antitermination allows expression of Late Genes from PR’ including phage proteins and lysis genes
-
virulent phages only undergo what life cycle?
lytic cycle
-
What is the key of lysogenic gene expression?
CI, the lambda repressor
-
What is not expressed from any of the promoters in the lytic cycle?
CI, the lambda repressor
-
About how many bp are in the lysogenic lambda genome?
48,000
-
The lambda repressor (CI) shuts off....
all other lambda genes except itself.
-
the lysogenic cycle gene expression ______ the same as the lytic cyle.
starts
-
The two delayed early genes in the lysogenic cycle gene expression is...
CII and CIII
-
PRE is not active...
on its own
-
The PRE must be activated by.....
CII
-
in the lambda repressor structure, the regions that make contact with the DNA are the...
alpha-helical regions
-
What part of the lambda repressor is responsible for dimerization?
The COOH-terminal domain
-
What part of the lambda repressor is responsible for DNA binding?
NH2 terminal domain
-
what is the basic structure of the lambda repressor?
helix-turn-helix
-
What does the repressor (CI) do once its made to shut off all lambda gene but its own?
It binds to operator sequences
-
What does CI binding to OR do to PR?
causes transcription towards cro and PRE towards CI.
-
What does CI binding to OR do to PRM?
- yields more repressor from PRM transcription
- shuts off ALL lambda gene except CI
-
When repressor is bound to OR1 and OR2 it shuts off...
PR and PL
-
Repressor bind to what to operaters almost equally?
OR1 and OR2
-
what operator does the repressor bind to the least?
OR3
-
When repressor is bound to OR1 and OR2 it shuts off PR and PL and activates...
PRM
-
What are the steps of gene expression in the lysodenic cycle?
- 1) Immediate Early Genes expressed PR and PL
- 2) N Mediated Antitermination of Delayed Early Genes Including CII (and CIII)
- 3) CII Activates PRE which yields a small amount of Repressor
- 4) CI binds to OR1 and OR2, which shuts off PR and PL and Activates PRM
- 5) All Lambda Genes are shut off except CI
-
CII Activates PRE which yields a small amount of...
Repressor
-
The one early gene that is key for lytic gene expression is...
Cro
-
The two delyaed early genes that are important for lysogeny is...
CII and CIII
-
Cro is a _________ protein
DNA binding
-
Cro is a DNA binding protein that binds to..
OR and OL
-
Cro will bind to _____ more than _____ and _____ more than _____.
- OR3 more than OR2
- OR2 more than OR1
-
When Cro occupies OR3 it shuts off...
PRM
-
The "Genetic Switch" is a race between....
CI (repressor) and cro
-
in the genetic switch, CI leads to .....
lysogeny
-
in the genetic switch, CI leads to lysogeny by binding to...
OR1=OR2>OR3
-
in the genetic switch Cro leads to ...
lytic
-
in the genetic switch, Cro leads to lytic by binding to...
OR3>OR1=OR2
-
What control whether CI or Cro wins in the genetic switch race?
An E.coli protein called HflA
-
what is HflA?
An e coli protein thats an ATP dependent protease cleaves CII
-
The Induction of lysogens, occurs in response to...
DNA damage
-
What occurs in response to DNA damage?
Induction of lysogens
-
The RecA protein is part of a ....
DNA damage repair system
-
What induces cleavage of Repressor (CI)?
RecA
-
RecA induces cleavage of....
Repressor (CI)
-
In RecA mediated cleavage, CI binds to OR1 and OR2 to activate ______ and repress _____.
-
E.coli O157:H7 contains a lysogen of a lambda like....
phage 933W
-
E.coli O157:H7 contains a _______ of a lambda like phage 933W
lysogen
-
With regard to promoting the lytic or lysogenic cycle, what would happen if the cro gene were missing from the λ genome?
The lysogenic cycle would occur because cro protein is necessary to initiate the lytic cycle.
-
With regard to promoting the lytic or lysogenic cycle, what would happen if the CI gene were missing from the λ genome?
The lytic cycle would occur because cI encodes the λ repressor, which prevents thelytic cycle.
-
With regard to promoting the lytic or lysogenic cycle, what would happen if the CII gene were missing from the λ genome?
The lytic cycle would occur because cII protein is necessary to initiate the lysogenic cycle.
-
With regard to promoting the lytic or lysogenic cycle, what would happen if the int gene were missing from the λ genome?
Both cycles could try to initiate, but the lysogenic cycle would fail because it would be unable to integrate into the host chromosome.
-
With regard to promoting the lytic or lysogenic cycle, what would happen if the CII and cro genes were missing from the λ genome?
Neither cycles could occur.
-
PRM and PR transcribe in ________ directions
opposite
-
The λ repressor will first bind to...
OR1 and then OR2.
-
The binding of the λ repressor to OR1 and OR2 inhibits transcription from...
PR
-
The binding of the λ repressor to OR1 and OR2 inhibits transcription from PR and thereby switches off...
the lytic cycle
-
Early in the lysogenic cycle, the λ repressor protein concentration may become so high that it will occupy.....
OR3.
-
When the λ repressorconcentration begins to drop, it will first be removed from...
OR3
-
The removal of the λ repressor from OR3 allows...
allows transcription from PRM and maintains the lysogenic cycle.
-
the cro protein has its highest affinity for OR3 so it ...
binds there first
-
The cro protine binding to the OR3 blocks...
transcription from PRM
-
The cro protine binding to the OR3 blocks transcription from PRM and thereby switches off...
lysogenic cycle
-
cro binding to OR1 or OR2 turns down...
the expression from PR
-
A mutation in PR causes its transcription rate to be increased 10-fold. Do you think this mutation would favor the lytic or lysogenic cycle?
It would first increase the amount of cro protein so that the lytic cycle would be favored.
-
When an E. coli bacterium already has a λ prophage integrated into its chromosome, another λ phage cannot usually infect the cell and establish the lysogenic or lytic cycle. Based on your understanding of the genetic regulation of the λ life cycles, why do you think the other phage would be unsuccessful?
A cell that has a λ prophage is making a significant amount of the λ repressor. If another phage infects the cell, the λ repressor inhibits transcription from PR and PL and thereby inhibits the early steps that are required for either the lytic or lysogenic cycles.
|
|
