Lambda

Question 1

2 impt struct

Answer 1

1. Head contains daDNA

2. Tail sheath

Question 2

Describes attachment

Answer 2

Tail fibre binds complementarily to specific receptor sites

Question 3

Describe penetration

Answer 3

Inject dsDNA;

Capsid remains outside

Question 4

Describe integration

Answer 4

dsDNA circularised

Question 5

3 ways that circularised dsDNA can be used for?

Answer 5

1. Prevents degradation of foreign dsDNA by host’s exonuclease
2. Circular phage DNA multiply and transcribe
3. Integrate into specific site on bacterial circular DNA by integrase
   - > prophage

Question 6

How prophage remains silent

Answer 6

• prophage gene codes for repressor protein

- > block expression of prophage gene

Question 7

Why a single infected bacterial cell can give rise to a large no of infected bacterial cells?

Answer 7

Prophage genome replicated tgt w bacteria genome via binary fission

=> propagate w/o lysine host cell

Question 8

How lambda enters lytic cycle?

Answer 8

Spontaneous induction of prophage

-> physical stress of bacterium

Question 9

What happened @cellular stress?

Answer 9

-repressor protein is destroyed by activated bacterial enzyme

Question 10

Describe

1. Early replication
2. Late replication

Answer 10

1. Virus dsDNA replicates and directs host’s metabolic machinery
   - > synthesis bacteriophage components
2. Pdtn of bacteriophage components and enzymes progress

Question 11

How is lambda release?

Answer 11

Bacterial coded enzyme breaks down peptidoglycan

->osmotic lysis
=> release