Gene Regulation in Eukaryotes Flashcards

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1
Q

Eukaryotes & prokaryotes regulate genes at __________

A

Transcription

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2
Q

Eukaryotes can also be regulates when?

A
  1. Post translation
  2. mRNA stability
  3. Translation
  4. microRNA
  5. Post-translation (protein modification, protein stability)
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3
Q

Transcription factor

A

Group of proteins that influence the ability of RNA polymerase to transcribe a gene

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4
Q

Two types of transcription factors that can regulate RNA polymerase to bind to the promoter switch from initiation stage & elongation are what?

A
  1. General Transcription factors (GTFs)
  2. Regulatory transcription factors (RTFs)
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5
Q

General transcription factors (GTFs)

A

Required for RNA polymerase to bind to the promoter & its progression to the elongation stage (needed for basal transcription)

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6
Q

Regulatory transcription factors (RTFs)

A

Serve to regulate the rate of transcription

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7
Q

Regulation in eukaryotes is similar to prokaryotes because they have what?

A
  1. Cis-factors (enhancer & silencers)
  2. Trans-factors (activators & repressor)
  3. mRNA processing, splicing, transport, & access to ribosome
  4. Protein transport to proper location
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8
Q

In eukaryotes a regulatory transcription factor can increase the rate of transcription when an _________ binds to an enhancer

A

Activator

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9
Q

In eukaryotes regulatory factors can decrease transcription when a _________ binds to a silencer

A

Repressor

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10
Q

Combinatorial Control

A

When a combination of different factors determines the expression of many genes

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11
Q

At the level of transcription what factors contribute to combinatorial control? All 5 factors can contribute to the regulation of a single gene

A
  1. An activator
  2. Repressor
  3. Small effector molecules
  4. Nucleosomes
  5. DNA methylation
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12
Q

Regulatory transcription factors (activators & repressors) recognize regulatory sequences that function as ________ or ________

A

Enhancers or silencer

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13
Q

Up regulation

A

When enhancers stimulate transcription by 10 to 1000 folds (times)

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14
Q

Down regulation

A

When silencers inhibit transcription

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15
Q

Regulatory transcription factors may exert their effects through _______

A

TFIID

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16
Q

TFIID

A

Is a general transcription factor that binds to the TATA box & is used to get RNA polymerase to bind to the promoter

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17
Q

Activator proteins can enhance the ability of TFIID to start transcription by interacting with ________

A

Coactivators

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18
Q

Coactivators

A

Proteins that increase the rate of transcription but doesn’t directly bind to the DNA

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19
Q

A repressor can inhibit the function of TFIID by preventing the TFIID from binding to the __________ or inhibiting TFIID ability to make RNA polymerase 2 bind to the promoter

A

TATA box

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20
Q

The function of a regulatory transcription factor can be modulated in what 3 ways?

A
  1. The binding of small effector molecules
  2. Protein-protein interaction
  3. Covalent modifications
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21
Q

________ can bind to a regulatory transcription factor & promote it to bind to DNA

A

Small effector molecules such as steriod hormones

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22
Q

Protein - protein interaction

A

The formation of dimers is used to control transcription (dimerization) (Joining two dimers to make one)

23
Q

Covalent modification

A

Can affect the function of regulatory transcription factors by attachment of a phosphate group

24
Q

What mutation will prevent gene activation?

A

Trans factors:

  1. When RTFs cant bind to enhancers
  2. When RTFs can’t bind with an effector molecule
  3. When RTFs can’t bind with GTFs

Cis factor:
1. When cis factors can’t bind to RTF

25
Q

_________ exerts their effects by binding to a regulatory transcription factor

A

Steriod hormones

26
Q

Chromatin Remodeling

A

Refers to dynamic changes in the structure of chromatin that occur

27
Q

____________ also depends on changes in chromatin structure which affect the ability of a transcription factor to gain access to & bind to their targeted sequences in the promoter

A

Gene Regulation

28
Q

_________ histones changes nucleosomes positioning composition & removal

A

Remodeling histones

29
Q

If the chromatin is in a ____________ transcription is decreased (or doesn’t happen at all)

A

Closed conformation

30
Q

If the chromatin is in an _______ transcription is increased

A

Open conformation

31
Q

_________ alters the position & composition of nucleosomes

A

Chromatin remodeling

32
Q

What are the 2 ways change chromosome strcuture

A
  1. Remodel histones
  2. Modifying histones (covalently)
33
Q

What are the two changes in the nucleosomes position?

A
  1. Change the position of a few nucleosome
  2. Change in the spacing of the nucleosomes over a long distance
34
Q

Histone eviction (type of modifying histones)

A

A histone octamer is removed

35
Q

Replacement with histone variants (type modifying histone)

A

A histone is replaced with a variant

36
Q

What are the standard histones?

A

H1, H2A, H2B, H3, H4

37
Q

What are the different histone variants?

A
  1. H10(variant for H1) linker histone used in chromatin compacting & gene repression
  2. macroH2A(Variant for H2A)- used in inactivated X-chromosome
  3. CenH3 - found in the centromere (variant for H3)
38
Q

What are the types of histone tail modifications?

A
  1. Acetylation
  2. Phosphorylation
  3. Methylation
39
Q

The types of ___________ interacts with DNA & changes the chromatin conformation (also interacts with other proteins)

A
40
Q

When tight DNA goes through ________ it becomes loose DNA

A

Acetylation

41
Q

________ can control transcription by having specific patterns for modification

A

Histone code

42
Q

Eukaryotic genes are flanked by ____________

A

Nucleosome free regions (NFR)

43
Q

In active genes the ______ & _______ is found at NFR

A

Promoter & terminator region (don’t have histones over them)

44
Q

In active genes the ______ & _______ is found at NFR

A

Promoter & terminator region (don’t have histones over them)

45
Q

__________ involves changes in nucleosomes position, composition, & histone modification

A

Transcriptional activation

46
Q

Describe the transcriptional activation process in eukaryotes genes for initiation & elongation

A
  1. The enhancer is in the promoter region where the activator bind to the enhancer
  2. Activators recruits chromatins remodelers (histones modification & loose conformation)
  3. Formation of pre-initiation complex is formed
  4. Elongation occurs where the histones ahead of the open complex are covalently modified by acetylation & evicted or partially displace. Behind the open complex, histones are deacetylated & become tightly bound to the DNA again
47
Q

DNA methylation

A

DNA structure modified by the covalent attachment of methyl groups

48
Q

__________ occurs on the cytosine base & usually inhibits gene transcription

A

DNA methylation

49
Q

DNA methylation occurs by an enzyme called ___________

A

DNA methyltransferase

50
Q

DNA methyltransferase

A

Which attaches a methyl group to the carbon at the # 5 position of the cytosine base forming 5-methylcytosine

51
Q

___________

A

DNA methylation turns genes, activators off & repressors on (methylation inactivates acitvators)

52
Q

__________ occurs at the CpG island which is just before the promoter (CpG also contain the enhancer where activator binds to)

A

Methylation

53
Q

In methylation a _______ binds to the methylated CpG island & it also binds a chromatin modifier to make a chromatin close (turn off a gene)

A

Repressor

54
Q

In an ________ chromatin a gene is on

A

Open