What is a characteristic of a bacterial promoter?

What is an example of a transcriptional control for gene X?

What is a rho independent termination?

DNA binding proteins serve as activators most like as _________.

Transcriptional regulators typically have what characteristics?

What factors lead to a positive regulation of the lac operon?

What does cAMP do to the protein CAP?

What are some true statements about prokaryotic promoters?

Most DNA binding proteins regulate gene expression in prokaryotes by ______.

Housekeeping genes are typically _______.

Draw where the sigma factor binds to the promoter sequence and the location of the RNA polymerase in a prokaryotic system

Explain how cAMP helps CAP regulate lac operon

why is the lac operon considered leaky

Why is a leaky expression of lacZYA beneficial when lactose levels are high.

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