BIO484 Exam 4. Already Passed

BIO484 Exam 4. Already Passed
general transcription factors (GTF) - =not integral part of polymerase, recognize and bind to
sequences in the promoter, attract the RNA pol II at the correct site, designated TFIIA/B/C,
necessary for basal transcription


regulatory transcription factors - =regulate the rate of transcription of target genes by binding to
the control elements


co-regulators - =do not directly bind to the DNA, but bind or modify other transcription
regulatory factors, control the recruitment and access to DNA of general transcription factors and
RNA pol II


two types of co-regulators - =co-activators and co-repressors


co-activator - =increases amount of transcription


co-repressor - =decreases amount of transcription


transcription factors have multiple domains which work to - =activate or repress gene expression


what are the transcription factor domains - =1. DNA binding domain
2. dimerization domain
3. ligand binding domain
4. activation/repression domain


which domain(s) do all transcription factors have - =DNA binding domain and
activation/repression domain


dimerization domain - =facilitates the formation of homodimers

,activation domain - =works to turn on transcription


repression domain - =works to turn off transcription


ligand-binding domain - =binds a ligand, changing the structure of the transcription factor and
activating it


hundreds to thousands of base pairs upstream or downstream of the transcription start site - =(left
to right)
enhancer/distal enhancer with TF
break
-200 to -50 is proximal promoter/enhancer with TF
-50 to 50 is core promoter with GTF


promoter - =a sequence of DNA to which proteins bind to initiate transcription of a single RNA
transcript from the DNA downstream of promoter


enhancer - =DNA sequences which are directly bound to transcription factors


proximal promoters/enhancers - =enhancers located close to the core promoter


distal enhancers - =enhancers that have a considerable distances from core promoter


general features of enhancers - =contain short sequence elements, and multiple elements are
often cluster together, elements frequently occur as inverted repeats of the same DNA sequence


YEAST GAL SYSTEM REGULATION
what does the yeast do - =makes use of extracellular galactose (gal) by importing and converting
it into a form of glucose to be metabolized

, YEAST GAL SYSTEM REGULATION
gal 3/4/80 - =encode proteins that regulate transcription of the enzyme-encoding genes


YEAST GAL SYSTEM REGULATION
in yeast cells lacking galactose ... - =gal genes are transcriptionally silent


YEAST GAL SYSTEM REGULATION
in presence of galactose (absence of glucose) ... - =the gal genes transcriptionally induced


YEAST GAL SYSTEM REGULATION
gal 1/2/7/10 - =part of the gal system pathway


YEAST GAL SYSTEM REGULATION
gal 1/2/7/10 have gal 4 binding sites, required for - =transcription activation


YEAST GAL SYSTEM REGULATION
if the gal 1/2/7/10 binding sites are deleted ... - =genes silent even in presence of galactose


YEAST GAL SYSTEM REGULATION
gal 4 domains function independently of one another - =no ligand domain


YEAST GAL SYSTEM REGULATION
gal 4 activity is regulated by gal 80 and gal 3 proteins - =normal function of gal 80 prevents gal
gene transcription
normal function of gal 3 promotes gal gene transcription
in absence of galactose, gal 4 inactive but can still bind to UAS elements, activity is repressed by
binding of gal 80 within gal 4 activation domain, gal 3 induced a conformation change in gal 80
which releases it from gal 4 to activate gal gene transcription