Bacteriophage

Question 1

What is a Bacteriophage?

Answer 1

Virus that infects bacteria

Question 2

Most Bacteriophages have?

Answer 2

dsDNA

Question 3

Bacteriophages can have RNA as a ___?

Answer 3

genome

Question 4

A virulent phage has how many reproductive options?

Answer 4

One

Question 5

What is the one wat a virulent phage can reproduce?

Answer 5

Lytic Cycle

Question 6

Lytic Cycle

Answer 6

Phage multiplies immediately upon cell entry. Lysis the bacterial host cell.

Question 7

Temperate Phages have how many reproductive options?

Answer 7

Two

Question 8

What are the two cycles that temperate phages utilize?

Answer 8

Lytic and lysogenic

Question 9

Lysogenic cycle

Answer 9

Phage integrates into host cell’s chromosome.

Question 10

What is lysogeny?

Answer 10

The relationship between a prophage and lysogenic bacteria

Question 11

When phage DNA integrates into bacterial host cells chromosome, what is its name?

Answer 11

Prophage

Question 12

Can a temperate phage change the phenotype of its host?

Answer 12

yes

Question 13

Temperate phage change to bacterial host cell surface achieves what? (Example provided in notes)

Answer 13

Bacteria become immune to superinfection

Question 14

Temperate phage change to make bacterial host cell a pathogen? (E.g. in ppt)

Answer 14

Phage may express pathogenic toxin/enzyme; cholera, diptheria

Question 15

What are two advantage of lysogeny for a virus?

Answer 15

Phage remains viable even if it does not replicate. Multiplicity of of infection ensures survival of host cell.

Question 16

What is the process called ‘induction’?

Answer 16

when conditions in the cell cause prophage to initiate synthesis of new phage particles

Question 17

What type of Bacteriophage is bacteriophage T4?

Answer 17

A virulent bacteriophage

Question 18

Phage life cycle culminates w/host cell bursting, releasing virions. What are the steps?

Answer 18

Absorption to receptor on outer membrane
Tail sheath lysozyme/central tube pierce the cell wall
Viral nucleic acid is injected into host cell through tube

Question 19

Phage Adsorption: attachment of phage onto host. Steps?

Answer 19

Tail fibers recognize receptor protein on cell surface
Baseplate settles down on surface
Shape change of baseplate tail to (24 to 12 rings)

Question 20

Phage DNA Entry Steps:

Answer 20

Central tube is pushed through cell wall
Baseplate contain lysozyme
Linear DNA is extruded from the head into host

Question 21

Bacteriophage T4 Life Cycle: Transcription -> early mRNA. What does this result in?

Answer 21

Production of viral encoded DNA-dependent DNA polymerase

Question 22

Bacterial T4 Life Cycle: Transcription -> late mRNA.

Answer 22

Translation of capsid and lysis proteins

Question 23

Temporal transcription regulated by:

Answer 23

Alternative E. Coli polymerase factors induced by virus
Early viral gene product stimulate transcription of some late viral genes
Genes w/related functions are usually separated and clustered together

Question 24

Early gene transcribed…

Answer 24

Counterclockwise

Question 25

Late gene transcribed...

Answer 25

Clockwise

Question 26

The T4 Genome/DNA: A large portion of the genome codes for replication-related products including...

Answer 26

Protein subunits of its replisome Enzymes needed for DNA synthesis (synthesis of HMC)

Question 27

What is hydroxymethylcytosine (HMC)?

Answer 27

A modified nucleotide replacing cytosine in T4 DNA

Question 28

HMC is chemically modified by glucosylation

Answer 28

Protects T4 phage DNA from E. Coli restriction enzymes. Enzymes that cleave DNA at specific sequences. Restriction is a bacterial defense mechanism used against bacteriophage infection

Question 29

Why is T4 DNA terminally redundant?

Answer 29

Base sequence repeated at both ends. Allows for formation of concatamers.

Question 30

What are concatamers?

Answer 30

Long strands of DNA consisting of several units linked together

Question 31

Concatamers allow for the cleaving of genome for...

Answer 31

Viral progeny packaging

Question 32

Complex self-assembly process involves viral proteins and host cell factors for ...

Answer 32

Capsid assembly

Question 33

Assembly/Release of T4 Phage Particles: what is the set of proteins that package DNA?

Answer 33

Packasome moves DNA into phage head Terminase complex generates double stranded ends. (Cuts concatemer and pushes DNA into head)

Question 34

Release of T4 Phage Particles: Assembly is followed by release in T4 E. Coli system, ~150 viral particles are released. What two proteins are involved in this process?

Answer 34

T4 lysozyme and Holin

Question 35

What does the T4 lysozyme do?

Answer 35

Attacks cell wall

Question 36

What does holin do?

Answer 36

creates holes in plasma membrane

Question 37

What type of Bacteriophage is a bacteriophage Lambda?

Answer 37

Temperature bacteriophage