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12 Cards in this Set
- Front
- Back
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Regulation of bacterial gene trascription rates... how is it done?
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Differential binding of optimal or non-optimal motifs.
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Consensus motif? non-consensus?
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Consensus -- an optimal sequence motif for binding
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What is an operon?
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coordinately regulated cluster of genes with related functions.
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Operator?
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which is a DNA nucleotide motif
- operator controls whether RNA Pol can pass by |
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Repressor protein, key regulator of operator? Where is it encoded? Is it allosteric? what does it do if active?
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- encoded outside of the operon
- allosteric protein - can be turned on or off - in its active form it complexes with operator & blocks Pol |
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How does the repressor block Pol?
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It binds with the operator when active, and does not allow Pol to pass, which means that no RNA is made.
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How does the LAC operon work (think lactose)?
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lac operon encodes enzymes that catabolize milk sugar - lactose
if no lactose to metabolize, the operon is turned off by having the operator blocked with the repressor. If lactose is present, the repressor becomes inactive, the operator lets the Pol by, and the RNA is made to degrade the lactose (operon on). |
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Other transcription regulation methods in prokaryotes?
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Use of different sigma factors for specific genes
- these sigma factors only made in certain environmental conditions - initiate transcription of genes with unique promoter motifs |
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What do anti-biotics do?
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They're anti bacterials. They target the translation process. The unique bacterial RNA Pol may also be a target (like the drug Rifamycin, makes the Pol inactive).
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Antibiotic resistance? What causes this?
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- occasional mutants make polymerase or translation proteins
that adjust to conformational changes made by antibiotic - antibiotic resistance genes are often carried on plasmids that can be passed between bacteria by conjugation |
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What are a few things that plasmids typically carry genes for?
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antibiotic resistance
metabolic pathways virulence (ability to cause disease) formation of a sex pilus |
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F-plasmid?
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Contains genes that encode for the sex pilius. It can pass this on to another, who can pass it on to another, and on and on.
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