Term
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Definition
| Amino acid used for protein synthesis |
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Term
| Bacteria live in fluctuating environments |
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Definition
| Bacteria can produce tryptophan by running a metabolic pathway via enzymes |
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Term
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Definition
| bacteria cease running metabolic pathway and making tryptophan |
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Term
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Definition
| run metabolic pathway and produce tryptophan |
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Term
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Definition
regulating enzyme activity via feedback inhibition
or
Regulating enzyme production by regulating gene expression (Tryptophan Operon) |
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Term
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Definition
| code for a polypeptide subunit of enzymes needed to make tryptophan |
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Term
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Definition
DNA base sequence preceding the coding genes
binding cite for RNA polymerase |
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Term
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Definition
DNA base sequence located within promoter
attachment site for repressor protein
controls access of RNA polymerase to coding genes |
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Term
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Definition
located elsewhere in genome
codes for repressor protein
usually constitutive (always "on") |
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Term
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Definition
allosteric protein that exhibits specificity for an operator
binds reversibly to operator
Blocks RNA polymerase binding to the promoter (blocks transcription)
trp repressor produced in an inactive form
i.e. has low affinity for operator |
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Term
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Definition
substance that converts repressor protein from inactive to active form
trp operon: corepressor is tryptophan |
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Term
| If tryptophan is absent from environment |
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Definition
The repressor remains inactive
RNA polymerase can bind to promoter
DNA is transcribed
Operon remains on
Bacterial cell produces enzymes for tryptophan production |
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Term
| Tryptophan present in environment |
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Definition
binds to and activates the repressor
binds to the operator
RNA polymerase cannot bind
DNA can not be transcribed
Operon turned off
Stops producing enzymes |
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Term
| Lactose is a disacharide made of |
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Definition
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Term
| Lactose present in environment |
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Definition
bateria need to make enzymes to catabolize the lactose
LACTOSE OPERON |
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Term
| lactose absent in environment |
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Definition
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Term
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Definition
beta galactosidase
hydrolyzes lactose into glucose and galactose |
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Term
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Definition
permease
protein that transports lactose into cell |
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Term
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Definition
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Term
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Definition
| binding site for RMA polymerase |
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Term
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Definition
| binding site for repressor |
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Term
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Definition
| produces active repressor |
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Term
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Definition
| allosteric protein that binds to the operator and prevents transcription |
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Term
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Definition
inactivate the repressor
e.g. allolactose=lactose |
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Term
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Definition
active repressor binds to operator
RNA polymerase can not bind to promoter
DNA cannot be transcribed
Operon is OFF
lactose catabolizing enzymes not produced |
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Term
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Definition
inactivates the repressor
repressor can not bind to operator
RNA polymerase can bind to promoter
DNA Can be transcribed
Production of enzymes for lactose catabolism
Operon is ON |
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Term
| Positive Gene Regulation works by |
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Definition
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Term
| Positive Gene Regulation utilizes: |
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Definition
activators
f: switch transctiption on |
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Term
CAP
Catabolite Activator Protein |
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Definition
activator for lac operon
inactive form
activated by cAMP |
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Term
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Definition
| glucose is the preferred energy source of bacteria |
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Term
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Definition
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Term
glucose absent
lactose present |
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Definition
[cAMP] high-> CAP is active
CAP binds to promoter->enzymes are produced |
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Term
| glucose and lactose present |
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Definition
[cAMP] low-> CAP is inactive
CAP cannot bind to promoter
RNA polymerase does not readily bind
very few lactose digesting enzymes are produced |
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Term
| Lactose operon under dual control |
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Definition
negative control via repressor/ OFF switch
positive control via CAP/VOLUME switch |
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