Exam 2: Gene Regulation in E. coli Flashcards Preview

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Flashcards in Exam 2: Gene Regulation in E. coli Deck (24)
1

what does it mean when genes are "expressed"

they are transcribed and make their product (RNA or protein)

2

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

3

RNA polymerase

makes RNA from a DNA template

works with other proteins

4

all promoters bind to...

RNA polymerase

5

stronger promotor binding raises...

transcription rate

6

how to determine promoter strength

depends on how strongly they bind to RNA polymerase

7

holoenzyme

transcription complex of RNA polymerase and different components for different transcription units

8

transcription factor

proteins interacting with the promotor

produce precise and specific transcription control

9

many proteins can influence the ...

holoenzyme

10

operon

transcription unit with multiple ORFs

make mRNA that code for multiple proteins

eukaryotes have a few, prokaryotes have many

11

lac. operon normal state of E. coli

no lactose, no transcription, no resources wasted

3 ORFs

12

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)

13

cAMP

cyclic AMP

adenosine monophosphate

14

glucose and cAMP

concentrations inversely related

high glucose, low cAMP

low glucose, high cAMP

15

CAP

catabolite activator protein

system keeps variety of other substrate-specific operons turned off if glucose is around

16

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

17

the lac operon is an .... operon

inducible

18

inducible enzymes

found in breakdown rxns

induced by substrates

19

trp operon normal state in E. coli

continual transcription

20

trp operon transcription controls

repressor binds if tryptophan binds to the repressor

prevents excess tryptophan production if it is present in high concentration

21

the trp operon is an ... operon

repressible

22

repressible enzymes

found in synthesizing reactions

repressed by end products

23

are the molecule-to-molecule binding interactions in these mechanisms reversible?

yes

they depend on affinity and concentration

24

do transcription factors regulate the transcription of other transcription factors?

yes