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17 Cards in this Set
- Front
- Back
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What are bacteriophages? |
Bacteriophages are viruses that infect bacteria. |
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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 |
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How many bacteriophages are present in the ocean? |
5 x 10^7 / ml |
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What are the functions of marine bacteriophage? |
1. influence biogeochemical cycles 2. prevent out break of bacterial populations e.g. algal bloom |
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When was bacteriphages discovered? |
1915-1917 |
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What is the characteristic of the nucliec acid in the majority of bacteriophages? |
dsDNA, non enveloped. |
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What is the function of the tail bone of a bacteriphage? |
to attach the phage to a host cell receptor |
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What is the function of the sheath of a phage? |
acts as a channel for the deliverance of the genome into host cell |
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What are the two types of life cycles in a bacteriophage? |
1. Lytic 2. Lysogenic |
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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 |
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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 |
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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. |
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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 |
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Is repression specific? |
YES |
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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 |
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List three importance of bacteriophages. |
1. an early model for molecular bio and genetics study 2. therapy-antibody resistance 3. important component for biotechnology |
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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 |
