Phage Lambda (λ)

Question 1

name 2 physical features on the λ phage

Answer 1

-isocohedral head
-noncontractile tail

Question 2

what is a bacteriophage?

Answer 2

viruses that infect bacteria

Question 3

what repressor proteins are key?

Answer 3

-CL protein
-Cro proteins

Question 4

what classification of bacteriophage is λphage?

Answer 4

ds DNA

Question 5

name an example of ssRNA

Answer 5

leviviridae

Question 6

cystoviridae is an example of what class of bacteriophage?

Answer 6

dsRNA

Question 7

what is a lysogenic phage?

Answer 7

temperate phage

Question 8

name 2 reproductive options

Answer 8

1-typically
2-lysogeny(remain within the host cell without destroying it)

Question 9

describe a summary of the prophage stage in lysogeny

Answer 9

phage genome integrates on host bacterial genome- on chromosome for (λ) or plasmids for (P1).most phage genes not expressed. prophage reproduced in synchrony.

Question 10

what is a lysogen

Answer 10

bacterial host infected w a prophage

Question 11

what are host cell lysogens immune to?

Answer 11

superinfections by the same virus-phage repressor

Question 12

decsribe the process of induction

Answer 12

under appropriate conditions, lysogen will lyse & release phage particles

Question 13

what altered conditions can leave to induction?

Answer 13

host cell damage

Question 14

what is a cryptic virus?

Answer 14

phage looses ability to leave the host via mutation

Question 15

where does the integration of phage λ take place?

Answer 15

attachment site in the bacterial & phage genomes (att)

Question 16

what happens on entry due to complementary base pairing in the lysogenic bacteriophage?

Answer 16

circularisation

Question 17

att int xis -are all responsible for what stage in organisation of transcripts?

Answer 17

integration & excision

Question 18

What’s responsible for recombination?

Answer 18

gam red

Question 19

what does the control region include?

Answer 19

CIII N cI cro CII

Question 20

O & P are responsible?

Answer 20

DNA replication

Question 21

what is lysis controlled by?

Answer 21

S

Question 22

Q is responsible for what stage?

Answer 22

late control

Question 23

where is early transcription initiated?

Answer 23

P1 & P2

Question 24

where is termination initated?

Answer 24

tL1 & tR1/tR2

Question 25

what allows anti-termination & expression of delayed early genes?

Answer 25

The product of gene N & Q(from Pr)

Question 26

tr3 is the site of what?

Answer 26

rightward transcript termination

Question 27

what happens if CI wins the race with Cro?

Answer 27

transcription blocked for cro gene, N & Q.lysogeny is established.

Question 28

what happens if Cro wins the race?

Answer 28

-Cro binds operating sites Or & OL, blocking transcription from the PR & PL -Represses Pm & CII synthesis. Blocks OI synthesis -prevents integration of the λ genome into the host chromosome

Question 29

what triggers induction?

Answer 29

drop in levels of λ repressor(CI) caused by UV exposure

Question 30

What does Excisionase (Xis)

Answer 30

-binds integrase (int) -enables integrase to reverse integration process

Question 31

what happens to the cohesive ends after infection?

Answer 31

theta θ mode-ligated together to form a circular molecule which replicates.

Question 32

rolling circle mode does what when switched over?

Answer 32

length linear DNA is generated, for further packaging into phage particles

Question 33

what is rolling circle replication required for?

Answer 33

production of the lytic cycle of replication-which generates multiple length linear DNA

Question 34

what is the replication forks' role

Answer 34

proceeds around the template

Question 35

where is the nick of the primer located?

Answer 35

3' -OH end

Question 36

why does temperate phage survive in a bacterium?

Answer 36

due to integration of their DNA into the host chromosome

Question 37

what can the temperate phage induce?

Answer 37

phenotype changes in the bacterium

Question 38

Escerichia coli O157:H7 saki strain description?

Answer 38

18 prophage genome,16% of entire genome

Question 39

what is a MORON?

Answer 39

after more DNA, phage often carries additional genes within elements(after more DNA)

Question 40

What impacts do MORONs have?

Answer 40

active players in cell physiology ----> become resistant to antibiotics,survive in other enviroments,produce toxins +other virulence factors

Question 41

where are morons identified?

Answer 41

within the prophage due to different G C content +own promoters & terminators

Question 42

resistance to quinolones & beta-lactams in E.coli mean what?

Answer 42

altered metabolic capabilities

Question 43

what allows E.coli to interact with & invade epithelial cells

Answer 43

phage λ protein

Question 44

what encodes survival of the host immune response-superoxide dimutase

Answer 44

gifsy-2 Salmonella prophage

Question 45

what protects against free radicals?

Answer 45

superoxide dimutase

Question 46

what protects E.coli from serum killing?

Answer 46

phage λ Bor protein

Question 47

exotoxins are involved with what?

Answer 47

bacterial pathogenicity

Question 48

give examples of defensive countermeasures bacteria use?

Answer 48

surface changes and restriction modifications

Question 49

helping defend ecological placing because...

Answer 49

phage are important led for acquisition of genes

Question 50

what does the decreased in fitness of lysogenic hosts mean?

Answer 50

metabolic burden to replicate extra DNA-lysis of the host after prophage induction

Question 51

what happens when prophage increase the fitness of lysogenic hosts?

Answer 51

immunity(phage repressor) & superinfection exclusion genes of prophage to protect lysogen

Question 52

give an extended description of the association of Lactobacillus delbruki

Answer 52

lytic phage rare, organism hard to transform with foreign DNA. strong barrier against intrusion of foreign DNA.

Question 53

what phage is readily detected in milk?

Answer 53

streptococcus thermophilis

Question 54

other features of streptococcus thermophilis include?

Answer 54

permissive to DNA transfer: few anti-phage mechanisms detected

Question 55

true or false proteins secreted from bacteria that are toxic to eukaryotic cells?

Answer 55

true

Question 56

thick mucopurulent, nasal discharge, fever, sore throat, swollen cervical lymph- are all symptoms of what?

Answer 56

corneybacterium diphtheride

Question 57

diphtheria is encoded by what?

Answer 57

roxin β-phage

Question 58

give examples of systemic symptoms of diphtheria

Answer 58

destroys parenchyma of heart, liver, kidneys or adrenal glands

Question 59

genetic exchange in the enviroment-sewage/water treatments

Answer 59

phage stx 1+2, dtx and sea widespread

Question 60

what infects cats,cattle,pigs,horses?

Answer 60

transduction of stx between E.coli O157:H7 and commensal s.aureus

Question 61

what does the transduction of stx between E.coli O157:H7 and commensal s.aureus produce?

Answer 61

enterotoxins SEA.SEB,SEC

Question 62

what does ampliphi treat?

Answer 62

pseudomonas aureginosa, cystic fibrosis, MRSA, infections of burns

Question 63

name the different serotypes of cholera

Answer 63

ISS, OI-el Tor, O139:bengal strain

Question 64

give the line knock on affect of the ingestion of V.cholera

Answer 64

adheres to colonies on small intestine -> CTX acts on mucosal cells(diarrhoea)

Question 65

whats encoded on a single gene locus regarding cholera?

Answer 65

incomplete enome of a filamentous bacreiophage CTX

Question 66

what does the CTX phage lack?

Answer 66

secretin but uses the host secretin encoded by type II secretion apparatus

Question 67

what integrated filamentous bacteriophage genome carries the cholera toxin gene?

Answer 67

CTX Φ on chromosome 1

Question 68

what does TCP stand for?

Answer 68

toxin co-regulated pilus

Question 69

what is TCP a receptor for?

Answer 69

phage CTX Ψ