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18 Cards in this Set
- Front
- Back
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Integrase |
An enzyme that inserts the phage DNA into the host cell chromes at a specific site |
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Prophage |
the integrated phage DNA |
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Repressor |
-prevents excision -prevents lyticphage genes from being expressed -maintains lysogenic state |
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Superinfection |
infection by the same type of phage |
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Phage induction |
lets the phage escape from a damaged host |
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what happens when the DNA-damaging agent such as UV light |
SOS repair system turns on,activates a protease |
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host protease |
destroys the repressor protein responsible for maintaining the integration of the prophage |
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What happens when protease destroys the repressor? |
allows prophage to be excised and it enters lytic cycle |
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What is the filamentous phage composed of? |
ssDNA, (+) sense DNA -M13 |
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M13’s replicative form is |
DNA polymerase -to make dsDNA |
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Extrusion |
the process where phage DNA is excreted throughpores - the coat proteins coatthe DNA to form nucleocapsids |
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Generalized transduction |
results from packing error -phages degrade host chromosomes and fragments can be mistakenly packed into the phage head -T4 lytic |
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Specialized transduction |
excision mistake made during transition from lysogenic to lytic phase -short piece of flanking bacterial DNA is removed (piece of phage DNA remains) -Excised DNA incorporated into phage heads -Lambda (λ) |
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Restriction Enzymes |
recognizes specific short nucleotide sequences in foreign DNA such as phage DNA, and then cuts the DNA molecule at these sequences -no phage replication |
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Modification Enzymes |
-methylate host sequences - NOT recognized by restrictionenzyme - enzymes accidentally methylate DNA - allow infection |
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CRISPR |
- phage spacer DNA goes into CRISPR - small RNAs bind to Cas proteins |
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Plaque assay |
used to quantitate phage particlesin samples: sewage, seawater, soil - soft agar inoculated with bacterial host |
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Attachment |
- virus binds to receptors (glycoproteins) - specific receptors (tropism) |
