Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
|
operon
|
-group of genes that functions as units.
-3 types of genes |
|
|
structural genes
|
in operon that code for enzymes in a metabolic pathwy.
|
|
|
operator gene
|
determines whether the structural genes will be transcribed or not.
|
|
|
promoter gene
|
the location where RNA polymerase binds to begin the process of transcription
|
|
|
repressor gene
|
codes for the production of a repressor protein that determines the activity of the operon as a whole.
|
|
|
when lactose is absent
|
a repressor protein binds a region known as the operator, blocking transcription of the structural genes.
|
|
|
when lactose is present
|
it is converted to allolactose, which binds to the repressor at an allosteric site. This prevents the protein from binding to the operator. This allows RNA plymerase to transcribe the structural genes.
|
|
|
presence of an inducer
|
inactivates the repressor, permitting the gene or operon to be transcribed.
|
|
|
enzyme induction
|
inducible gene isn't transcribed unless a specific inducer inactivates its repressor. code for enzymes in catabolic pthway.
|
|
|
repressible operons
|
usually turned on. anabolc pthways
|
|
|
Intracellular tryptophan levels low.
|
Repressor protein is inactive to prevent transcription b/c it can't bind to the operator
|
|
|
Intracellular tryptophan levels increase.
|
the a.a. trytophan (corepressor) binds to an allosteric site on the repressor. The resulting form of the repressor binds to the operator region, blocking transcription of the operon until trytophan is again required.
|
|
|
TATA box
|
promoter region in eukaryotes.
|
|
|
UPEs
|
upstream promoter elements. more present..more strongly gene is expressed
|
|
|
enhancers
|
dna sequences that increase transcription rate
|
|
|
transcription factors
|
stimulate transcription. must be present for enhancers and UPEs to be active.
|
|
|
heterochromatin
|
tightly condensed chromatin. genes in this region are turned off.
|
|
|
euchromatin
|
decondensed. actively transcribing mRNA, switched on.
|
|
|
transcription factors
|
stimulate transcription. must be present for enhancers and UPEs to be active.
|
|
|
heterochromatin
|
tightly condensed chromatin. genes in this region are turned off.
|
|
|
euchromatin
|
decondensed. actively transcribing mRNA, switched on.
|
