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17 Cards in this Set

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What are bacteriophages?

Bacteriophages are viruses that infect bacteria.

What are the properties of a bacteriophage?

1. Host dependent


= need host machinery for protein synthesis


2. host specific


= bacteriophage infect specific range of hosts

How many bacteriophages are present in the ocean?

5 x 10^7 / ml

What are the functions of marine bacteriophage?

1. influence biogeochemical cycles


2. prevent out break of bacterial populations e.g. algal bloom

When was bacteriphages discovered?

1915-1917

What is the characteristic of the nucliec acid in the majority of bacteriophages?

dsDNA, non enveloped.

What is the function of the tail bone of a bacteriphage?

to attach the phage to a host cell receptor



What is the function of the sheath of a phage?

acts as a channel for the deliverance of the genome into host cell

What are the two types of life cycles in a bacteriophage?

1. Lytic


2. Lysogenic

What are the steps in the lytic cycle?

1. Attachment


2. injection of genome into host


3. transcription and translation of genome


4. replication


5. assemble components


6. cell lysis and release phage

What are the steps in the lysogenic cycle?

1. Attachment


2. injection of genome into host


3. repression and integration of phage genome into host genome


3. host cellular replication


4. induct

What are the main differences between lytic and lysogenic cycle?

lytic cause cell lysis and release phages.


Lyogenic cause cellular replication.


lytic fully ecpress viral genes. Lysogenic genes are switched off.


Lytic are virulent phage and lysogenic are temperate phage.

How does repression on a phage genome work?

1. phade genome encode protein "repressor"


2. repressor bind to phage DNA operator site


3. turn off most phage genes EXCEPT REPRESSOR GENE


4. repressed genome is integrated into host genome

Is repression specific?

YES

What are the two types of phage resistance? give examples.

1. Genetically engineered


e.g. Per (phage encoded resistance)


2. natural occuring


e.g. abortive interference = prevent DNA rep

List three importance of bacteriophages.

1. an early model for molecular bio and genetics study


2. therapy-antibody resistance


3. important component for biotechnology

Compare use of phage and antibiotics to treat diseases.

Phage > antibiotics


- specific


- will not develop resistance


- will not cause secondary infections


- inexpensive and easy production




Antibiotics > phage


- do not need to be specific