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15 Cards in this Set
- Front
- Back
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two criteria for classiying bacteriophages
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phage morphology and nucleic acid properties
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lytic cycle
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-cycle of reproduction for double-stranded DNA phages
-phage life cycle that culminates with host cell bursting, releasing virions |
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virulent phages
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phages that lyse their host dring the reproductive cycle
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the one-step growth experiment
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-mix bacterial host and phage
-brief incubation (attachment occurs) -dilute greatly (released viruses cant infect new cells) -overtime, collect sample and enumerate viruses |
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adsorption to the host cell and penetration
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-receptor sites -->specific RECEPTORS on host to which viruses attach
---> specific ATTACHMENT SITES on each virus (can be proteins, lipopolysaccharides, teichoic acids) |
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synthesis of phage nucleic acids and proteins
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-SEQUENTIAL process
--->EARLY mRNA synthesis --->synthesis of proteins that enable T4 to take over the hsot cell --->phage DNA replication --->LATE mRNA synthesis (encode capsid proteins and other proteins needed for phage assembly) |
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how is early mRNA made?
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-some by regular host RNA polymerase
-others by modified host RNA polymerase |
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what are the concatamers in T4 DNA?
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long strands of DNA consistnig of several units linked together
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T4 proteins that bring about lysis of host
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-endolysin: attacks peptidoglycan
-holin: produces lesion in cell membrane |
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lysogeny
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-nonlytic relationship between a phage and its host
-usually involves INTEGRATION of phage genome into host DNA ---->PROPHAGE=integrated phage genome ---->LYSOGENS (lysogenic bacteria)= infected bacterial host ---->temperate phages=phages able to establish lysogeny |
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induction
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-process by which phage reproduction is initiated
-results in switch to LYTIC CYCLE |
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lysogenic conversion
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-change in host PHENOTYPE induced by lysogeny
(ex: modification of Salmonella lipopolysac structure/production of diptheria toxin by corynebacterium diptherieae |
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lambda phage
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-double stranded DNA phage
-temperate phage -linear genome with cohesive ends |
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If lambda repressor wins...
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-lambda genome inserted into E.coli genome
(integrase:catalyzes integration) |
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induction
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-triggered by drop in levels of lamda repressor
---> caused by exposure to UV LIGHT and chemicals that cause DNA DAMAGE -excisionase (binds integrase and enables integrase to reverse integration process) |
