Flashcards in Exam 2: Gene Regulation in E. coli Deck (24)
what does it mean when genes are "expressed"
they are transcribed and make their product (RNA or protein)
are most genes being transcribed all the time?
no, they have to be turned on or off
output also has to be adjusted up or down
makes RNA from a DNA template
works with other proteins
all promoters bind to...
stronger promotor binding raises...
how to determine promoter strength
depends on how strongly they bind to RNA polymerase
transcription complex of RNA polymerase and different components for different transcription units
proteins interacting with the promotor
produce precise and specific transcription control
many proteins can influence the ...
transcription unit with multiple ORFs
make mRNA that code for multiple proteins
eukaryotes have a few, prokaryotes have many
lac. operon normal state of E. coli
no lactose, no transcription, no resources wasted
lac operon transcription controls
repressor, unbinds when lactose present (good)
CAP protein must be bound to promotor, and cAMP must be bound to CAP for this to happen
if glucose present there is low cAMP (bad)
glucose and cAMP
concentrations inversely related
high glucose, low cAMP
low glucose, high cAMP
catabolite activator protein
system keeps variety of other substrate-specific operons turned off if glucose is around
why does CAP work
high glucose = low cAMP
other things that need cAMP won't be transcribed if glucose is high
therefore, glucose is the primary focus for E. coli
the lac operon is an .... operon
found in breakdown rxns
induced by substrates
trp operon normal state in E. coli
trp operon transcription controls
repressor binds if tryptophan binds to the repressor
prevents excess tryptophan production if it is present in high concentration
the trp operon is an ... operon
found in synthesizing reactions
repressed by end products
are the molecule-to-molecule binding interactions in these mechanisms reversible?
they depend on affinity and concentration