Section 2 Pt. 2

Question 1

Tailed phages have: (which kind of genome)

Answer 1

linear ssDNA

Question 2

_____ have long, thick, contractile, rigid tails (T4)

Answer 2

Myoviruses

Question 3

______ have long, non-contractile, flexible tails (λ lambda)

Answer 3

Siphoviruses

Question 4

______ have short, non-contractile tails (T7)

Answer 4

Podoviruses

Question 5

Phage T7 is a 1- _______
2- one of the original viruses studied by __________
3- model _____ virus
3- has _____ shape

Answer 5

1- podovirus (short tail)
2- the phage group
3- Model lytic virus
4- icosahedral

Question 6

Phage T7 can only replicate in cells that ____ _____ have the _____ _____

Answer 6

DO NOT have the F Plasmid

Question 7

Phage T7 has __ core proteins and ___ tail fibres

Answer 7

3 core proteins and 6 fail fibers

Question 8

tail fibers of Phage T7 bind to _____ on the outside of the cell and then core proteins are pushed through ___ to let __________

Answer 8

bind to LPS outside the cell
core proteins pushed through tail
Only small amount of DNA goes in at first

Question 9

DNA of phage T7 is packaged in capsid and it enters the cell in specific order/direction: (2 steps)
1- only ___________ enter after the core goes through envelope

2- cell’s _________ transcibes the first gene and as it moves along is pushes against CM and pulls more genome in

Answer 9

1- only 850 bp of DNA let In from the left end (has a promoter)

2- Cell’s RNA ploymerase

Question 10

Phage T7 class I protein functions: (3)

Answer 10

1- invade host RNA polymerase (no more host genes expressed)
2- inactivate host restriction enzymes (protects phage DNA)
3- Code for Viral RNA polymerase to make class II and III and pulls genome in

Question 11

Phage T7 class II protein functions: (2)

Answer 11

1- degradation of host DNA
2- replication of phage DNA
** class II has way more promotors so its forced to make more of them genes

Question 12

Phage T7 class III protein functions: (3)

Answer 12

1- virion structural protiens
2- cell lysis
3- one of the proteins binds to viral RNA pol and makes it bind to III promotors better than class II

Question 13

Phage T7 packaging: DNA replication generates copies of DNA with small gaps making ____ _____ ______ combined to make a _________

Answer 13

the end problem
concatemer

Question 14

Cotacatemer is then ____ into single genomes during DNA packaging in a ______ fashion so that class I end is facing out

Answer 14

cut out, Directional

Question 15

Temperate bacteriophage Lambda λ discovered in _____ by _______ from Ecoli stain K12

Answer 15

1951, Esther Lederberg

Question 16

strain K12 is a λ _____ (able to generate lysis) and in it, λ exists as ________

Answer 16

lysogen
prophage

Question 17

Phage λ (unlike T7 - always lytic) can either enter _____

Answer 17

Lytic cycle or lysogenic cycle

Question 17

Phage λ has a pattern of organization common in tail phages were ______

Answer 17

genes are lined like how proteins will end up in the particle

Question 18

Stain λPaPa is a recombinant version that is missing _______ and makes _________ in soft agar

Answer 18

Missing tail fibres
Large plaques (This is because it doesnt have tail fibers that slow it down so it spreads faster)

Question 19

Strain λPaPa is missing the tail making protein due to a ______ _______

Answer 19

frameshift mutation

Question 20

receptor on the cell is ——–, which is a maltose transporter expressed in presence of maltose
recognized by J-protein on —– of Ur-λ bringing maltose inside

Answer 20

LamB
tail

Question 21

Ur-l adsorbs to cells better than the PaPa version will bind and infect cells grown in ________ (PaPa won’t)

Answer 21

glucose

Question 22

with the use of tail fibers, the phages are much more effective at binding to cells
Strain λPaPa: in the situation where the receptor is present at low amounts, they are _______ of _______ without the tail fibres

Answer 22

incapable of attaching

Question 23

different phages have tails with different lengths but for any specific ________ phage (long non-contractile flexible tails, e.g. lambda) the particles all have the same tail length

This is because its doesn’t have tail length determining ______ protein

Answer 23

siphovirus

H protein

Question 24

A ____ _______ protein (more protein = longer tail) in sequences of siphovirus

Answer 24

tape measure protein
siphovirus

Question 25

Phage λ DNA has 12 nt ssDNA ends called ____ _____ on the ends
Genome circularizes after entering the cell through the complimentary cos sequences

Answer 25

cos sites (cohesion)

Question 26

Phage λ: after infection and circularization of the DNA, 2 genes are expressed: ____ and _____

those help make more genes such as ___

Answer 26

N and cro

cll

Question 27

Phage λ: If lysis:

Answer 27

replication, structural and lysis genes turned on

Question 28

Phage λ: If lysogeny: only 2 genes subsequently expressed – cI and int

Answer 28

– cI and int
DNA integrates (by protein encoded by int), then only cI is expressed during lysogeny