Lecture 3/5 Flashcards
what is basal level of transcription?
whatever occurs at a rest-like state (usually really low or not at all)
what does the RNA pol complex bind to to get the basal level of transcription?
TATA box (also in proks) – usually the most important, ~25-30nt upstream to the start of transcription
CAAT box ~70-80nt upstream
GC box ~110 nt upstream
what process is affected by mutations in core promoter sequences? Why?
transcription, as it can cause bad binding of the RNA pol complex
what are enhancers/repressors?
sequences within the DNA to which a transcription factor can bind to activate or repress transcription
where on the chromosome are enhancer/repressor sequences?
they can be anywhere along the chromosome, near or far to the +1 region
can you find enhancer/repressor sequences in an intron?
yes
can you find enhancer/repressor sequences in an exon?
no
does the orientation of enhancer/repressor need to be in one direction
no, it can be reversed
are enhancer sequences gene-specific?
no, they might be used by multiple genes
are promoters gene-specific?
yes
what needs to bind to the enhance sequence in order to get transcription above basal rates?
transcription factors (which are proteins)
is basal transcription the same for every gene?
no
what does the binding of a repressor cause?
it can block the binding of RNA pol complex to promoter region
What is one thing the RNA pol complex looks for to know where to bind?
TATA box (and TATA binding protein)
How might enhancers that are really far from each other be connected to the transcription complex?
it loops the DNA
what happens to transcription if cohesin comes in to loop the DNA and it blocks access to the activating protein?
the expression of the gene is different, lowered
what is one thing that changes gene expression in different tissues?
presence or lack thereof of different transcription factors
what is acetylcholine used for?
it’s used at neuromuscular junctions for muscle contractions
what are nestled genes?
genes transcribed in the same direction using the same promoter sequences, one is often in the intron of another gene
what are nestled genes in euks similar to in proks?
operons
what is the order of how acetylcholine gets to the muscles?
synthesized in the cytoplasm, packaged into synaptic vesicles, released at the synapse
what is an example of nestled genes?
unc-17 gene is located in an intron of cha-1 gene
do genes grouped together usually have anything in common?
yes, they often have common functions and are regulated by common elements
can nestled genes share an exon
yes, but likely not translating to a protein
