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19 Cards in this Set
- Front
- Back
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The lac operon in ? has a coding region for 3 ? necessary for the use of ? as a food source.
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E. Coli
proteins lactose |
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The 3 ? of the lac operon are only needed when ? is available and the normal food source ? in in short supply.
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proteins
lactose glucose |
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The ? region of the lac operon has two switches. One is the ? binding site, which gets switched on only when ? levels are low. The other is the ? site which only gets switched on when ? is present.
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regulatory
CAP glucose operator lactose |
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Both the ? and ? switch must be on for to allow expression of the lac operon genes.
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CAP switch
Operator switch |
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The ? binding site is next to the promoter for the lac operon. When the level of glucose is low, a high level of a compound called ? builds up in the cell.
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CAP
cAMP |
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cAMP and a protein called CAP form a ? and bind at the ? site on the lac operon.
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complex
CAP |
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Once the cAMP/CAP complex binds to the CAP regulatory site on the lac Operon, the lac operon bends allowing ? to bind at the ?
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RNA polymerase
Plac(promoter site) |
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When the glucose level is high there is not enough ? so nothing binds at the ? site, which equals no bend. This keeps ? from binding at the promoter site, preventing expression of the lac operon genes.
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cAMP
promoter RNA polymerase |
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The operator site is also next the Plac(promoter site). When lactose is absent a ? protein is bound to the operator and prevents RNA polymerase from transcribing the gene code for metabolizing ?.
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repressor
lactose |
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When lactose is present, a lactose isomer called ? will bind to the repressor protein, which changes its comformation and removes it, preventing it from binding to the ? site.
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allolactose
operator |
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When ? levels are low and ? is present RNA polymerase will bind to the ? region and carry out transcription.
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glucose
lactose Plac/promoter site |
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The ? switch is on when glucose levels are low
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CAP
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? is the promoter region for the lac operon.
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Plac
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The ? site is where the repressor protein will sit if lactose is absent
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operator
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The ? is always attached at the operator site, unless lactose is present.
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repressor protein
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What is the layout of the Lac operon?
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Pl / l / CAP / Plac / O / Z / Y / A
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CAP protein and cAMP bind together at the CAP bind site and ? the DNA, allowing ? to bind.
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bend
RNA polymerase |
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When lactose is absent the ? protein halts synthesis of the lactose catabolism enzymes.
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repressor
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The ? is the piece that can turn on an inducible operon.
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substrate
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