What is a characteristic of a bacterial promoter?
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What is an example of a transcriptional control for gene X?
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What is a rho independent termination?
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DNA binding proteins serve as activators most like as _________.
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Transcriptional regulators typically have what characteristics?
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What factors lead to a positive regulation of the lac operon?
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What does cAMP do to the protein CAP?
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What are some true statements about prokaryotic promoters?
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Most DNA binding proteins regulate gene expression in prokaryotes by ______.
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Housekeeping genes are typically _______.
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Draw where the sigma factor binds to the promoter sequence and the location of the RNA polymerase in a prokaryotic system
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Explain how cAMP helps CAP regulate lac operon
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why is the lac operon considered leaky
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Why is a leaky expression of lacZYA beneficial when lactose levels are high.
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How can liver cells and neurons have the same genome, but different functions?
depends on gene regulation
What is required for prokaryotic transcription
promoter, terminator
DNA and RNA
structurally the same but differ in ribose sugar and U vs T bases
DNA and mRNA
mRNA has same sequence in coding DNA but T is replaced by U
RNA polymerase
transcribes DNA message to RNA
needs a promoter
general transcription factors (eukaryotes) and sigma factors (prokaryotes)
help RNA pol to find correct promoter
prokaryotic gene organization
1 promoter for several genes that function in same or related pathways
called operons
eukaryotic gene organization
1 promoter per gene
RNA polymerase + sigma factor =
holoenzyme
sigma factors recognize ____
DNA promoter sequences upstream from transcrption start site (+1)
(-35 and -10)
sigma70 in E. coli
drives expression for cell growth and survival (housekeeping genes)
alternate sigma factors expressed to stress or other triggers
after being positioned on the DNA, RNA polymerase unwinds the DNA helix. Where does the initial unwinding occur?
-10 box of promoter
more AT bonds --> less energy
After transcription initiation RNAP ___
adds NTPs still, synthesizes RNA transcript, synthesizes RNA 5' to 3'
why is a terminator needed
because RNA polymerase doesn't know when to stop
where are GC rich sequences found
3' untranslated end (UTR) of mRNA and bound to Rho protein
Rho proteins and RNAP
RNA wraps around Rho and pulls it closer to RNAP, the contact between these 2 signals to stop transcription
prokaryotic terminator
hairpin of GC with a set of UUUU at the 3' end
transcription regulators usually interact with DNA thru
non covalent interactions
major vs minor groove
major shows more bases than minor
activators
bind to specific DNA sequence and activate downstream genes
repressors
bind at DNA sequence and inhibit gene transcription
usually blocks RNAP
lac operon
controls expression of genes used in lactose breakdownuu