BIO484 Exam 4 (Answered) 230
Questions and Correct Answers,100%
Verified. 2025/2026.
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
YEAST GAL SYSTEM REGULATION
how does gal 4 activate gene expression
1. interacting with subunits of the protein complexes having roles in transcription initiation
2. recruiting proteins that modify chromatin structure, allowing RNA pol II and other proteins access
to the DNA
GENE EXPRESSION
prokaryotes structure of genome
single, circular genome accompanied by accessory DNA
GENE EXPRESSION
eukaryote structure of genome
genome found in chromosomes nucleosomes structure limits DNA accessibility
GENE EXPRESSION
prokaryotes size of genome
small
GENE EXPRESSION
eukaryotes size of genome
large
Questions and Correct Answers,100%
Verified. 2025/2026.
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
YEAST GAL SYSTEM REGULATION
how does gal 4 activate gene expression
1. interacting with subunits of the protein complexes having roles in transcription initiation
2. recruiting proteins that modify chromatin structure, allowing RNA pol II and other proteins access
to the DNA
GENE EXPRESSION
prokaryotes structure of genome
single, circular genome accompanied by accessory DNA
GENE EXPRESSION
eukaryote structure of genome
genome found in chromosomes nucleosomes structure limits DNA accessibility
GENE EXPRESSION
prokaryotes size of genome
small
GENE EXPRESSION
eukaryotes size of genome
large
