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20 Cards in this Set
- Front
- Back
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Examples of ssDNA phages
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phiX-174, M13
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ssDNA mechanism
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converted to dsDNA by host DNA polymerase to make replicative intermediate
M13 is secreted from cell |
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RNA phage mechanism
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Codes for RNA replicase, enzyme to replicate RNA genome
Capsid proteins made and ssRNA is packaged |
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RNA phage example and characteristics
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MS2 - small, tailless, phages of E. coli, only 3-4 genes
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dsRNA phage example
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Phi-6 - infects Pseudomonas
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dsDNA mechanism
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Lysogenic - stays in the host cell until INDUCTION
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dsDNA example
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Lambda phage
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Prophage
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viral genome of temperate phage
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Temperate phage
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capable of lysogeny
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Induction
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switching to lytic cycle
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Mechanism of Lytic or Lysogenic decision?
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cl and cro compete for same binding site on phage DNA
cl = represses synthesis of all genes --> lysogenic cro = represses synthesis of cl --> lytic |
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When bacteria isn't growing well, it enters which cycle?
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Lysogenic because small amount being made at low level
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Lysogenic conversion
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change induced in host phenotype by presence of prophage due to expression of additional genes from prophage
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Applications of bacteriophages
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Alternative treatment for bacterial infections because self-replicating, smart drugs and narrow specificity
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Holin
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enzyme that pokes holes
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lysin
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enzyme that breaks host cell wall peptidoglycan
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Examples of lytic and lysogenic dsDNA
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lytic = T4
lysogenic = lambda |
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Classification of bacteriophages
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Morphology - Head shape, contractile, noncontractile tails, tailless, filamentous
nucleic acid properties dsDNA, ssDNA, ssRNA, dsRNA |
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What receptor sites are there for phages on bacteria?
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T-even: proteins, lipopolysaccharides
Teichoic acids, cell wall components Carbohydrates Sex pilus |
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Lytic Life Cycle steps
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1) Adsorption into host cell and penetration
2) Synthesis of phage nucleic acids and proteins 3) Phage DNA is replicated 4) Assembly of phage particles 5) Release of phage particles |
