Sets 16 Flashcards
how many RNA pol are used for transcription in eukaryotes?
3
what RNA pol is used for protein transcription
RNA pol II
what is the core promoter and what is it composed of?
a part of the promoter close to the gene coding region; it has the +1 region which transcription starts and the the TATA box
where is the TATA box and how many nucleotides does it have?
at the -30 region and has about 7 nucleotide
what are the 4 cis acting regulatory regions ?
core promoter( TATA box)
CAAT box (@ 74-94)
GC box (@ 74-94)
Enhancer
what is an enhancer ?
a reg site on DNA that can be close or far way from the core promoter and increase transcription by 100x
what 2 basal factors must bind to core promoter ?
TATA box binding protein (TBP)
TBP-associated factors (TAF)
how does TAF, RNA Pol & TBP bind to the promoter ?
TBP bind to the promoter and the TAFs bind to the TBP and RNA pol bind to all
what are transcription factors
certain proteins that can control the rate of transcription by binding to the DNA
what binds to enhancers ?
transcriptional activators
what are the two domains on the activators ?
the DNA binding domain
transcription activation domain
what can bind to activators what do they do ?
co activators and they can unwrap the DNA on the promoter region
what is lightly packed DNA
Euchromatin
what is tightly packed DNA?
Heterochromtin
can promoters have multiple enhancers
yes
what is needed to be an activator ?
you need to be a dimer to be able to bind to the enhancer
what is an example of a co activator
steroid hormones
what does a co-activator do ?
binds to the activator and changes its shape to be able to bind to DNA enhancer
How does an activator stabilize transcription ?
by interacting with the other proteins TBP & TAF and RNA pol
what 4 things must the activator do to be able to turn on the gene transcription
- Binds to the hormone
- Become a dimer
- be in nucleus
- bind to enhancer
what do transcriptional repressors do ?
its lowers transcriptional activity
what are the two ways that transcriptional repressors lower transcription?
binding to enhancer
binding to activator
what 2 things can a co-repressor do ?
1.interact with the protein and RNA pol and prevent them form the promoter
2. tightin and wrap DNA ( histones)
why is DNA wrapped tightly
bc of lysine positive charge and phosphate negative charge
what 2 things affect gene expression?
- chromatin structure
- DNA methylation patterns
what are the two type of chromatin structure modifications?
1.Acetlyation
2. Methylation
what does acetylation on the chromotin do?
it has a negative charge so it interfers with the Histone and DNA electric charge and unwinds it a little to help transcription
what does methylation on the chromatin do ?
methylation on the chromatin bring in other factors that hold “lock in” the chromatin in place which keeps it tight and keep it permanently OFF
what is dark bands ?
heterochromatin meaning genes in region is not transcribed
what are TAD’s (Topological associated domains)
puts regulator elements in a loop so certain enhancers and promoters can interact with another
what is DNA methylation ?
block of C&G rich islands that can be methylated and stop transcription there
what is epigenetic phenomena ?
a change in gene expression that is not related to sequence changes (methylation)
what is gene imprinting ?
dna methylation being passed on the children
