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My Packs: (WIZEPREP) (BIO 2581) > Chapter 6: 6.7 Introduction to Regulation of Gene Expression > Flashcards

Chapter 6: 6.7 Introduction to Regulation of Gene Expression Flashcards

1
Q

Why are not all genes expressed at the same time?

A

Organisms regulate gene expression in order to:
* Conserve energy and resources when certain gene products are not required

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2
Q

What levels can gene expression be regulated?

A
  1. Epigenetic
  2. Transcriptional
  3. Post-Transcriptional
  4. Translational
  5. Post-Translational
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3
Q

What do epigenetic and transcriptional regulation involve?

A

Whether a gene (DNA) gets to be transcribed into RNA

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4
Q

List:

Examples of epigenetic and transcriptional regulation

A
  • Whether the gene is physically accessible (epigenetic)
  • Presence of special molecules called transcription factors to recruit RNA polymerase (transcriptional)
  • RNA splicing and control of RNA stability (transcriptional)
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5
Q

What does translational regulation involve?

A

Involves controlling mRNA translation into proteins

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6
Q

What does post-translational regulation involve?

A

Involves modification of the expressed protein, modulating its activity

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7
Q

Define:

Constitutively expressed genes

A

Genes that are expressed continuously

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8
Q

True or False:

Constitutively expressed genes are not regulated

A

False

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9
Q

How can expression levels of constitutively expressed genes be regulated?

A
  1. Promoter strength (transcriptional regulation)
  2. mRNA half-life (translational regulation)
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10
Q

How is a promoter determined to be “stronger”?

A

Has a sequence closest to the consensus sequence
* Bounds more often and more strongly by RNA polymerase
* Leads to more transcripts

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11
Q

True or False:

Only eukaryotes can have all 3 levels of gene regulation

A

False, eukaryotes and prokaryotes can both have all 3 levels of gene regulation

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12
Q

Unlike eukaryotes, bacteria can have - ——- —- between a promoter and a terminator or ——– —– – ——

A
  • A single gene
  • Multiple genes in tandem
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13
Q

What is an operon?

A

In prokaryotes, multiple genes in tandem

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14
Q

Describe:

Single Protein Genes in Prokaryotes

A
  • One promoter, coding region and terminator
  • Encodes for one protein

(2 points)

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15
Q

Describe:

Operons (Multi-Protein Gene) in Prokaryotes

(3 points)

A
  • One promoter, several protein coding regions, on terminator
  • Encodes for multiple proteins
  • Several start and stop codons to define the beginning/end of each protein
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16
Q

Where is an operator located?

A

Directly upstream or downstream of the promoter

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17
Q
  1. What binds to the operator?
  2. What does it do?
A
  1. Regulatory proteins
  2. Controls when RNA polymerase binds to promoter to activate transcription
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18
Q

What is responsible for transcriptional regulation?

A

Operator and Regulatory Proteins

19
Q

What is translational regulation?

A

Means affecting mRNA before it gets translated into proteins

20
Q

What are some methods of translational regulation?

A
  • mRNA is degraded before it gets translated
  • mRNA have short RNAs bind to prevent ribosome from binding
21
Q

When does post-translation regulation occur?

A

Occurs after translation of mRNA into proteins

22
Q

What are some methods of post-translational regulation?

A
  • Degradation of produced proteins to directly control their levels in the cell
23
Q

What is a degron?

A

A sequence on the protein that designates it for degradation

24
Q

How does degradation of produced proteins in post-translation regulation work?

A
  • Recognin binds to the degron sequence of a protein
  • Brings protein to a proteosome
25
Q

What is a proteosome?

A

A group of proteins that degrade other proteins

26
Q

Why can transcription and translation occur simultaneously in prokaryotes?

A

They do not have a separate compartment for the nucleus

27
Q

What are the regulatory proteins that control gene expression in many common prokaryotic systems called?

A

Activators and Repressors

28
Q

What is the basic structure of a regulatory protein?

(3 points)

A
  • Contains a DNA binding region
  • Binds to the operator next to the promoter
  • Can also have a allosteric site that controls the DNA binding site
29
Q

True or False:

Some regulatory proteins have an allosteric site that is controlled by the DNA binding site

A

False, the allosteric site CONTROLS the DNA binding site

30
Q

Define:

Activators

A

Promotes binding of RNA polymerase to the promoter to activate transcription
* Involved in positive regulation

31
Q

Define:

Repressors

A

Prevents RNA polymerase from binding to the promoter to inhibit transcription
* Involved in negative regulation

32
Q

What can activators and repressors be influenced by?

A

Small molecules:
* Inducers
* Inhibitors
* Co-repressors

33
Q

Define:

Inducers

A

Promote gene expression by inactivating repressors or activating activators

34
Q

Define:

Inhibitors

A

Prevent gene expression by inhibiting activators

35
Q

Define:

Co-repressors

A

Prevent gene expression by activators repressors

36
Q

True or False:

Activators are involved in negative regulation

A

False, they are involved in positive regulation

37
Q

True or False:

Repressors are involved in positive regulation

A

False, they are involved in negative regulation

38
Q

How do inducers promote gene expression?

A

By inactivating repressors OR activating activators

39
Q

How do inhibitors prevent gene expression?

A

By inhibiting activators

40
Q

How do co-repressors prevent gene expression?

A

By activating repressors

41
Q

Describe:

Positive regulation

A

Activators may be always bound to DNA promoting transcription
* In other cases, activators are not bound and they require an inducer to bind to DNA

42
Q

Describe:

Negative regulation

A

Repressors may be always bound to DNA inhibiting transcription
* In other cases, repressors are not bound and they require a co-repressor to bind

43
Q

What would be required to stop positive regulation?

A

An inhibitor

44
Q

What would be required to stop negative regulation?

A

An inducer

My Packs: (WIZEPREP) (BIO 2581) (30 decks)

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