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24 Cards in this Set
- Front
- Back
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A ? operon can be turned on and a ? operon can be turned off
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inducible
repressible |
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The ? operon is the best understood cell system for explaining control through genetic induction
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lac
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The lac operon regulates lactose ? in E. cole
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metabolism
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Name the three important features of the lac operon:
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regulator
control locus structural locus |
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The ? is a gene that codes for a protein capable of repressing the operon called a ?
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regulator
repressor |
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The control locus/regulatory region has two switches the ? and ?
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promoter/CAP site
operator/ O site |
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In the control locus the ? is recognized by RNA polymerase and the ? is a sequence that acts as an on/off switch for transcription.
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promoter
operator |
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In the structural locus there are ? genes each coding for a different enzyme needed to ? lactose.
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3
catabolize |
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The two signals that induce the lac operon are ? and ?
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lactose
cAMP |
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CAP = ? The CAP/cAMP complex binds to the CAP site of the lac-operon and stimulates ?
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catabolite activator protein
transcription |
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P-lac =
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promoter region for lac operon
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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 ? and the ? bind together to form a complex and then bind to the CAP binding site bending the DNA which allows ? to bind.
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CAP
cAMP RNA polymerase |
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When lactose is absent the ? protein halts synthesis of lactose catabolism enzymes.
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repressor
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?- lactose binds to the repressor protein allowing the O site to be switched on.
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Allo
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One of the enzymes ?, hydrolyzes the lactose into its monosacchrides (glucose and galactose), a membrane transport protein called a ? brings lactose across the cell membrane.
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B-galactosidase
permease |
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The ? is the piece of the puzzle that can turn on and inducible operon.
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substrate
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A ? operon is normally in the on mode and will be turned off only when the nutrient is no longer required
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repressible
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The excess nutrient serves as a ? needed to block the action of the operon.
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co-repressor
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examples of repressible operons are the ? operon and the ? operon.
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arg
trip |
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If the lac I gene is mutated such that the repressor no longer binds to the operator, the operon would never be repressed, and transcription would be carried out continuously. This is known as ?
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constitutive transcription(always transcribing)
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lacZ encodes for ? an intracellular enzyme that cleaves the disaccharide lactose
into ? and ?. |
β-galactosidase
glucose and galactose |
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lacY encodes for ?, a membrane-bound transport protein that pumps ? into the cell.
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β-galactoside permease
lactose |
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? is an isomer of lactose and is the inducer of the lac operon. It binds to the repressor changing its conformation and releases it from the Operator "O" site which allows transcription to continue.
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Allolactose
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