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12 Cards in this Set
- Front
- Back
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Virulence factors are _______. |
mechanisms of pathogenesis. |
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What two things are required for regulation of virulence genes? |
a protein and a signal. |
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What are regulatory signals for virulence genes? |
-iron availability: i.e. diptheria toxin expressed when iron is low -temperature: high temp 37C often a signal that bacteria have entered human host -contact with eukaryotic cell: specific ligands, triggers expression of type 3 protein secretion system -quorum sensing: high population density allows for accumulation of certain compounds in external environment. |
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What are regulatory proteins for virulence genes? |
repressors or negative regulators
-DtxR binds iron and represses transcription of diptheria toxin gene.
Positive regulatory proteins/activators
-can be a two component system including a sensor and transducer. Sensor is usually a kinase that phosphorylates itself and the transducer. -i.e. PhoP/PhoQ controls virulence in salmonella
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How do bacteria often create antigentic variation? |
through gene rearrangements that create differing fimbriae |
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How does Neisseria Gonorrhoeae confer antigentic variation? |
- pilin protein and opacity protein (outer membrane protein), vary among different N. gon
-one complete pilin gene, pilE, can be expressed and incomplete genes are silent. Changes in expression of the pilin protein result from a silent genes recombining with homologous sequences of pilE.
This is often due to transformation. |
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How is genetic information transferred during transformation? |
cells take up "naked" DNA and integrates it into its chromosome. DNA is probs from spontaneously lysed cells.
cell first becomes competent to take up DNA. once taken up, the naked DNA will recombine with regions of the same sequence. |
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In N. gonorr, if ______ recombines with _______, no new pilus protein will be formed. |
pilS, pilS |
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Missense? |
alter the codon with different AA |
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nonsense? |
introduce stop codon |
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frameshift? |
one or two nucleotides added or deleted, completely alters downstream sequence. |
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conditional mutations? |
missense that have phenotype only under growing conditions. |
