Topic 10 Flashcards

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1
Q

What does transcription regulation involve in prokaryotes

A

A single activator or repressor protien

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2
Q

How many rna polymerase to prokaryotes have, where does transcription and translation happen

A

1 type rna pol
Prokaryotes have no nucleus so in cytoplasm at the same time

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3
Q

Where does mRNA synthesis occur

A

At the +1 site next to the promoter

Atg (start codon is further down stream)

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4
Q

How does transcription initiation and elongation happen in ecoli

A

A sigma factor brings the 5 subunit rna pol and positions it at the promoter

Then sigma factor leaves and elongation in 3’ to 5’ direction happens

(New mRNA is 5-3’

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5
Q

What are the two types of termination in prokaryotes

A

Factor independent termination
Rho dependent termination

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6
Q

What is factor independent termination

A

Doesn’t need rho protiens
Gc rich dna which is followed by an A rich code makes the gc from a loop and the unstable AAAAAA code causes rna pol to detach from transcript

Gc and au terminate transcription

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7
Q

What is rho dependent termination

A

The rho factor (protien) see a c rich sequence in the dna and then release rna pol from the template

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8
Q

What are characteristic of bacteria in relation to gene expression

A

They need to get and break down sugars from the environment, they use it as a carbon source

The conserve energy by only making the enzymes they NEED for improper and metabolism when the sugar is present

They recognize environmental condition (whether lactose present) and respond to them (by activation or repression of genes)

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9
Q

What is the promoter

A

Dna sequence the rna pol binds to to start transcription

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10
Q

What is the activator where does it bind

What type of regulation is this

A

Protien that brings the rna pol cooler to the promoter

Binds to the activator binding site

Promotes transcription

Positive

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11
Q

What is the repressor where does it bind

What type of regulation is this

A

block rna pol from binding to promoter OR block it from moving along the dna

Bind to the operator on dna

Negative

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12
Q

If activator cant bind to activator binding site:

A

No transcription OR low/basal level of transcription

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13
Q

If repressor can’t bind to operator

A

If binds , no transcription

No binding so transcription occurs

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14
Q

What is an allosteric effector

A

Molecules that bind to the allosteric site of regulatory protiens

Some regulatory protien with the effector bind and some without the effector bind

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15
Q

What does the effector help with

A

Presence/ absence of it can help the cell respond to the environment by changing the conformation of regulatory protiens and helping them bind or not bind

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16
Q

What is the example of effector

A

Ex. for genes that control lactose metabolism, The effector is lactose

Lactose (the effector) binds to the repressor and prevent repressor from binding.

This cause rna to be made

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17
Q

What is an operon

A

Linked genes that are controlled by one promoter

All involved in the same function (metabolizing lactose)

Genes are turned into single mRNA

Either all or none of the gene products (enzymes) will be made

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18
Q

What is the lac operon

A

The operon needed for transport and metabolism of lactose

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19
Q

What are the protein coding genes in the lac operon

A

ZYA

MAKE

B-galctosidase, permease, transacylease

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20
Q

The protiens are needed for lac metabolism, what do each do

A

Permease (Y) : transports lactose into cell

Beta galactosidase (Z): changes lactose to allolactose then cleave lactose

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21
Q

What is the “I” gene is the location of the gene important

A

The gene that encodes (makes) the repressor protein

No, just the protien it make is important

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22
Q

What is transacting elecmwnt

A

When something effects gene expression of distant genes (on diff dna than itself) as well as nearby genes (on same dna as itself)

23
Q

What is cis acting element

A

Affects expression of nearby genes (on same dna as itself)

24
Q

What are cis acting element examples
What are transacting examples

A

Operator and promoter
Protiens

25
Q

What does negative regulation do

A

Involves only the repressor

Turns lac operon on or off

Makes rna or not

26
Q

What does postive regulation do?

A

Involves the activator and fine tunes the expression levels of the lac operon

More/Less expression

Involves the presence of glucose

27
Q

What happens to the lac operon if there’s no lactose present

A

Doesn’t need to make metabolizing protiens

Repressor bind to operator, stops transcription, no ZYA made

28
Q

What happened to the lac operon if lactose is present

A

Need to make metabolizing protiens

Lactose (inducer) makes allolactose (effector) which attached to repressor and stops is from binding to operator

Rna pol transcribe ZYA

29
Q

What does noninduced conditions mean

A

Repressor is non induced, so it’s binds to operator and ZYX made

30
Q

What does induced conditions mean

A

Repressor is induced, lactose present, repressor doesn’t bind to Operator, ZYX made

31
Q

If Z- what does this mean

A

Inactive Z, no z made no matter what

Non induced, no z
Induced, no z

32
Q

What is a constitutive mutation ?

A

Lac operon is on (proteins are made) where the inducer is present or not

Oc : means in non induced condition, protiens still made

33
Q

What else other than lactose can we use as inducer

A

IPTG

34
Q

What is the special thing that happens to make F’ plasmids

A

When the F factor (HRF) exits the chromosome it came from, it picks up some of the chromosomes dna

The F factor plus the picked up dna is the f’ plasmid.

35
Q

What is the bacterial cell that has f’ plasmid inserted into it called

A

Merozygote

(Partial diploid)

36
Q

Is Oc mutation cis or transacting

A

Cis, only affect what it’s attached to

If attached to Z+, Z always expressed in no induced and induced conditions

37
Q

What does I + mean

A

Repressor is there, regular conditions

38
Q

What type of mutation is I-, what does it mean

A

Constitutive

If it’s I-, lac operon is always on, expression in every condition,

39
Q

Is I+/I- cis or trans acting

A

Trans acting if present it affects everything , I+ dom over I-

40
Q

What is iS mutation

Trans or cis

A

Super repressor, it resist effect of inducer

Affects the allosteric site

So in non induced and induced condition, repressor always bind operator and no expression

Trans

41
Q

If iS and I+ what’s dominating

A

Is

42
Q

Oc is _______to is

A

Epistatic

Oc masks the effect of Is

Repressor can’t bind beats repressor isn’t affected by inducer

43
Q

What is the preffered energy source for prokaryotes, why

A

Glucose because energy capture from it is more efficient

If glucose is there, The cell conserves it energy and resources by reducing expression of the enzymes needed to process lactose

44
Q

If gluscose it present:

A

If the lac operon is turned on, it has minimal expression

45
Q

If glucose not present

A

If lax operon turn on, Enhanced expression because no glucose so it needs to use lactose

46
Q

What is the effect of high cAMP

A

It activate the lac operon (more expression)

47
Q

High glucose what happens to camp
Low glucose?

A

Low cAMP because glucose stop conversion of atp to camp, cap doesn’t bind, low lac expression

High camp because conversion isn’t inhibited, cap binds, enhances lac expression

48
Q

What is cAMP amd CAP

What is the CAP-cAMP complex

A

Allosteric effector for CAP

CAP is an activator protein, bind to the cap binding site in promoter when also bound to camp

Enhances rna pol transcription

49
Q

What are two way the lac operon can turn on

A

Presence of inducer (lactose, IPTG)
Constitutive mutation (Oc or I-)

50
Q

If glucose and lactose present what happens
If just glucose
If just lactose

A

Minimal expression of lac operon
No expression of lac operon
Enhance because (camp-cap)

51
Q

CAP+ AND CAP- are cis or trans?

A

Transacting

Cap+ dom over CAP-

52
Q

What does you need for enhanced expression

A

No glucose and a functional CAP

53
Q

In the promoter is P- what happens to the operon

A

Everything down stream of the promoter is gone