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MICRB 265 > 4-3: Transcriptional Regulation > Flashcards

4-3: Transcriptional Regulation Flashcards

1
Q

What is regulation

A

Controlling the abundance/activity of gene products
How cells adapt to environment

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2
Q

How is transcription initiation regulated

A

Control whether or not RNAP binds a promotor and transcribes (or the rate at which this occurs)

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3
Q

What protein largely regulates intiation

A

Transcription factors

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4
Q

What is sensing

A

Know which genes to turn off/on based on cues from envrionment

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5
Q

Most regulatory proteins are…

A

DNA-binding proteins

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6
Q

DNA-binding proteins must have what kind of domain… e.g.?

A

DNA-binding domains
Helix-turn-helix

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7
Q

What is recognized by DNA binding proteins

A

Consensus sequence

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8
Q

Transcription factors that promote transcription are…

A

Activators (bind DNA at promotor & recruit RNAP) “positive control”

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9
Q

Transcription factors than inhibit transcription are…

A

Repressors (bind DNA and prevent RNAP from binding, or prevents initation once bound) “negative control”

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10
Q

What is the sequence bound by the repressor called

A

Operator (after promotor region)

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11
Q

How is transcription regulated allosterically

A

Molecule binds activator or repressor to activate it

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12
Q

What are inducers

A

“Turn on” activator proteins (or inactivate repressors)

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13
Q

What are corepressors

A

Activate repressor proteins

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14
Q

What is an inducible system

A

System that is off by default, can be turned on

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15
Q

What is a repressible system

A

One that is on by default, can be turned off

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16
Q

What is a repressor protein that controls the expression of arginine biosynthesis operon

A

ArgR

17
Q

How does ArgR function in low and high arginine levels

A

Low = not bound by arginine, does not bind DNA, transcription of arginine proceeds

High = arginine binds ArgR. so it binds the operator and prevents transcription

18
Q

The machinery for breaking down lactose is encoded by the…

A

Lac operon

19
Q

What is the repressor of lac operon

A

LacI repressor protein

20
Q

What does LacI do when lactose is available vs absent

A

Available = lactose isomer (allolactase = inducer) binds LacI and inactivates it

Absent = LacI binds lac operator preventing transcription of lac operon (because it would make machinery for lactose breakdown; there is none present = wasted energy)

21
Q

What happens to the lac operon in the presence of glucose

A

cAMP production inhibited

Lac operon requires CRP (cAMP receptor protein) to bind cAMP. Together they would bind the promotor region & recruit RNAP

22
Q

What does the Lac operon require

A

Lactose and low glucose levels

23
Q

cAMP is a…

A

Signaling molecule/second messenger

24
Q

What is a signaling molecule

A

Produced in response to a signal, regulate processes in cell

25
Q

What is ppGpp

A

Signaling molecule produced in response to aa starvation. Shuts down protein synthesis and induces aa biosynthesis

26
Q

What is quorum sensing

A

Chemical communication: sensing local density of cells through secretion/detection of specific molecules

27
Q

Why is quorum sensing important

A

Coordinate group behaviours like biolfilm formation, virulence

28
Q

What are the molecules secreted in quorum sensing. How do they work

A

Autoinducers
Only accumulate at high density = group

29
Q

Name an autoinducer

A

Acyl homoserine lactones (AHL)

30
Q

What are the proteins used in two-component regulatory system

A

Sensor kinase

Response regulator

31
Q

What is sensor kinase

A

Cytoplasmic membrane protein. Senses signals that activate kinase. Add P to response regulator

32
Q

What is the response regulator

A

Active once phosphorylated by sensor kinase. Binds DNA to regulate expression of genes (activate/repress)

33
Q

What is a local vs global regulator

A

Local regulator = control expression of limited number of genes

Global regulator = regulate large numbers of different genes in response to signal

34
Q

Complete set of genes controlled by a given regulator

A

Regulon

35
Q

Archaea transcription regulation…

A

Similar to bacteria

36
Q

sensing local density of cells through secretion/detection of specific molecules

A

Quorum sensing

MICRB 265 (34 decks)

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