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Exam 1 Notes > Gene Regulation > Flashcards

Gene Regulation Flashcards

1
Q

How goes transcription occur in bacteria?

A

RNA polymerase binds to the promoter region

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2
Q

Constitutive Genes

A

Genes that are always expressed in the cell. Housekeeping genes.

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3
Q

Where does the majority of regulation in bacteria take place?

A

Transcriptional level

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4
Q

The operator

A

Area upstream of the promoter. Binding site for proteins that help to regulate gene expression.

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5
Q

Repressors

A

Bind to operator to prevent RNA polymerase from initiating transcription

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6
Q

Activators

A

Bind to an operator and allow RNA polymerase to initiate transcription

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7
Q

LacZ

A

Beta-galactosidase. Protein that is produced when lactose is present. Hydrolyzes lactose to glucose and galactose

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8
Q

LacY

A

Permease. Allows for active transports of lactose across cell membrane.

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9
Q

LacA

A

Transacetylase. Acetylase lactose.

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10
Q

LacZ, LacY, LacA

A

Genes that code for products that are involved in the catabolism of lactose.

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11
Q

What is the role of lac?

A

To break down lactose

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12
Q

LacI

A

Encodes a protein that shuts the system down when lactose is not present

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13
Q

What is the inducer for the lac operon?

A

Allolactose (isomer of lactose)

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14
Q

LacZ-, LacY-, LacA-

A

Structural gene mutations that lead to non-functional proteins

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15
Q

LacP-

A

Non-functional promoter, RNA polymerase can’t bind

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16
Q

LacOc

A

Nonfunctional operator, repressor can’t bind. Constitutive mutation.

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17
Q

LacI-

A

Non functional repressor, unable to bind the operator and turn off transcription

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18
Q

LacIs

A

Super repressor, unable to dissociate from operator. System is always off.

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19
Q

Negative control

A

When a repressor is used to turn the system off (Lac repressor)

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20
Q

Positive Control

A

When an activator protein is used to increase the efficiency of transcription

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21
Q

What is e.colis favorite carbon source?

A

Glucose, it is more efficient. lac is not on in presence of glucose

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22
Q

The hunger signal

A

Binding of CAP/CRP to the promoter, allowing transcription to occurs . CAP or CRP is first activated by cAMP. Lac operon is not expressed without the hunger signal. Must have lactose and the hunger signal for it to be expressed.

23
Q

Cis regulatory elements

A

DNA binding sites. On the actual DNA. Can bind transcription factor or enhancers.

24
Q

Trans regulatory elements

A

Modify expression of genes that are distract from the gene that created them. Typically transcription factors or enhancer binding proteins. Bind to Cis. Analogues to LacI

25
Q

Consensus Sequence

A

Sequence among many genes that isn’t exact, but it is similar

26
Q

Basal promoter sequence

A

Cis regulatory element. Bind transcription factor proteins which are associated with RNA polymerase. Include that CAAT and TATA box.

27
Q

Proximal control regions

A

These bind transcription factor proteins and are near the promoter

28
Q

Enhancer sequence

A

Are found far away from the promoter

29
Q

What does the basal transcription machinery do?

A

Allows a low level of expression

30
Q

What do proximal promoters do?

A

Increase expression and provide specificity

31
Q

What do enhancer binding transcription factors do?

A

Provide more specificity and amplify expression further

32
Q

Bending of DNA

A

Allows an enhancer binding protein to interact with the transcription factor and enhance transcription by RNA polymerase II

33
Q

DNA Binding Domain

A

Area on trans element transcription factor that only binds specific DNA

34
Q

Dimerization Domain

A

Two transcription factors that have been bound together to form a functional DNA binding unit.

35
Q

Activator/repressor Domain

A

Binds to the enhancer binding protein and modulates their function

36
Q

What are the three transcription factors that must dimerize to function?

A

Zinc finger, helix-turn-helix, and leucine zipper

37
Q

What are the three modes by which transcription factors can act as repressors?

A

Competition, quenching, and blocking

38
Q

Competition

A

Binding of the repressor to the enhancer sequence competes for the DNA binding site of the activator

39
Q

Quenching

A

Repressor protein binds to and interferes with the DNA binding domain of an activator protein. Now the activator cannot bind the enhancer sequence.

40
Q

Blocking

A

Repressor binds to the activation domain of activator protein and prevent it from interacting with the basal transcription machinery. May reduce transcription levels

41
Q

Response elements

A

Short sequences of DNA within a gene promoter region that are able to bind a specific transcription factor and regulate transcription of gene. Turn on/off genes

42
Q

Hypoxia Response Elelements

A

HIf1-a and HIF1-b dimerize and bind to DNA sequences to regulate expression of genes. HIF1a is degraded in the cytosolic under normoxia. Binds to DNA in the nucleus.

43
Q

Mac/myc

A

Regulatory system for switching between gene activation or repression.

44
Q

In the absence of Myc…

A

Max form a homodimer and it represses gene transcription

45
Q

In the presence of Myc…

A

A Myc/Max heterodimer if formed to activate gene expression

46
Q

Myc Overexpression

A

Distrusts the equilibrium between activation and repression of genes and can lead to cancer. Impairs differentiation and promotes cell proliferation.

47
Q

Burkitt Lymphoma

A

Caused if Myc is controlling the immunoglobulin promoter and enhancer control system.

48
Q

Drosha

A

Processes long primary miRNA to pre-miRNA hairpin structures

49
Q

Dicer

A

Further processes the pre-miRNA to ssRNA and initiates the formation of the RNA induced silencing complex (RISC)

50
Q

What is the main function of miRNA?

A

To silence genes by preventing translational machinery

51
Q

What are the two modes by which miRNA regulates translation?

A

Inhibition of translation on the ribosome or degradation of the target mRNA

52
Q

siRNA

A

Short interfering RNA. Regulates expression at the mRNA level. Processed by dicer.

53
Q

What is the main function of the activated GR?

A

Up-regulates the expression of anti-inflammatory genes in the nucleus and repressed the expression of pro-inflammatory proteins in the cytosol.

Exam 1 Notes (10 decks)

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