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Microbiology > Control of Gene Expression > Flashcards

Control of Gene Expression Flashcards

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Biology 101 flashcards
1
Q

list example operons

A

Lac
Arp
Trp

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2
Q

operator

A

allows RNA Pol to access DNA strand and start replication

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3
Q

repressors

A

regulatory proteins that bind to operator

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4
Q

operon senses glucose levels, sugar/carbon source

A

lac operon

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5
Q

gene expression cleaves lac operon to

A

allolactose (inducer)

interacts with the repressor

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6
Q

when inducer is bound to repressor what happens at operator?

A

it is not bound to operator

you need Cap to promote transcription

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7
Q

CAP

A

catabolite repression/global regulation

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8
Q

requirements for transcription on lac operon

A

CAP active and allolactose bound to operator

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9
Q

what happens when: lactose but no glucose

A

Allolactose is inactive, not bound

CAP is bound to CAP site

transcription occurs

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10
Q

what happens when neither lactose or glucose is available

A

transcription is blocked by repressor

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11
Q

what happens when lactose and glucose are available

A

transcription is inhabited by lack of CAP

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12
Q

what happens when lactose is not available but glucose is

A

Allalactose is bound

CAP is not bound

transcription is inhibited by lac of CAP and presence of repressor

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13
Q

CAP requires ___ to bind

A

no glucose

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14
Q

Allalactose requires ___ to bind

A

no lactose

will not be bound if lactose is present

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15
Q

CAP activity is modulated by

A

cAMP

levels of cAMP are controlled by adenyl cyclase (converts ATP to cAMP) – must have high levels of adenyl cyclase to get lots of cAMP so you must have low glucose

adenyl cyclase active only when little or no glucose is present

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16
Q

large quantities/high levels of tryptophan acts as ___

A

co-repressor of Trp Operon

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17
Q

Trp operon is on when

A

tryptophan is low

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18
Q

activity of tryptophan as a corepressor of Trp Operon

A

binds to repressor protein and blocks transcription (binds operator and blocks RNA Pol)

19
Q

Trp expression is regulated by:

A

repression (on and can be turned off) and attenuation

20
Q

attenuation

A

alteration of translation to alternate transcription

formation of termination loop that causes dissociation of Pol thru putting pressure on

21
Q

regulatory protein or Arb protein

A

AraC

also regulated by global regulation

22
Q

AraC

A

regulator that does both

activates transcription and turns off transcription

3 binding sites

23
Q

absence of Arb

A

results in bending of DNA and 2 AraC form a dimer

24
Q

Arb is available

A

Arb binds

AraC releases

results in dimer of AraC bound to Arb at key site to promote transcription

25
Q

Riboswitches

A

way to regulate gene expression

many systems

results in folding of leader sequence to determine if transcription continues or is terminated

depends on RNA and ability to form 2’ structure

26
Q

Gram - and riboswitch

A

can either free up shine delgarno so that 16s can bind or not (influences what happens)

27
Q

Riboswitches regulate translation of ___ in gram -

A

mRNA

28
Q

mechanisms of Riboswitches

A

binding to metabolite which alters structure

OR binding to a ligand to alter

29
Q

which bacteria have OmpC and OmpF

A

Gram -

outer membrane, so they must have outer membrane protein cores

30
Q

OmpF

A

opening of lager pore

allows more to flow through

31
Q

opening of a smaller pore to allow less diffusion is which of the Omp?

A

OmpC

32
Q

Regulation of Omp

A

depending on environment, upregulation/rexpression of 1 and inhibition of expression of other

33
Q

Mechanisms of expression of Omps

A

micro RNA (OmpF, binds)

2 component systems (sensor kinase – senses environment -gut or nah- which then causes phosphorylation of response regulator (ompR))

34
Q

OmpR

A

response regulator (protein 2)

35
Q

EmpZ

A

sensor kinase of OmpC/OmpF system

36
Q

how do you determine if clockwise or counter clockwise

A

methylation or ligand binding

37
Q

ligand binding > methylation

spinning =

A

run, so moving counter clockwise

38
Q

methylation >

A

attractant has already bound, and used up what’s there

tumble, stimulates clockwise rotation

39
Q

CheA

A

phosphorylates

sensor kinase

40
Q

to continue on a run, not going to spin

A

CheA is NOT phosphorylated

41
Q

When high [attractant] proteins are:

A

CheR= methylated

CheA= phosphorylated

42
Q

CheR

A

adds methyl groups

43
Q

CheB

A

removes methyl groups

promotes continuation of run

Microbiology (8 decks)

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