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Microbiology > Genetics #3 > Flashcards

Genetics #3 Flashcards

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Biology 101 flashcards
1
Q

Why regulate genetics?

A
  1. Saves materials

2. Saves energy

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2
Q

What are 2 ways gene expression is regulated?

A
  1. Transcriptional Initiation

2. Translation

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3
Q

Regulates activity of enzymes and proteins between active and inactive forms

A

Post Translational Regulation

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4
Q

What are the 3 primary ways Bacteria and Archaea regulate transcription?

A
  1. Constituive Gene Regulation
  2. Inducible Gene
  3. Repressible Gene
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5
Q

Gene regulation that… uses housekeeping genes that are transcribed all the time at low levels to replace old proteins that are at the end of their life

A

Constitutive Genes Regulation

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6
Q
  • Genes that are expressed (transcribed) only when certain specific substances (inducers) are present in the environment
  • Most commonly involved in catabolism
A

Inducible Genes

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7
Q

Genes that are normally expressed but repressed (shut down gene expression) when certain substances (corepressors) are present in the environment
-Most common in biosynthesis

A

Repressible Genes

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8
Q

For a gene to be transcribed, the promoter of that gene must be… (2)

A
  1. Accessible to the RNA polymerase

2. The RNA polymerase must then bind to the promoter

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9
Q

To regulate transcription of a gene, a cell can control… (2)

A
  1. Access to the promoter

2. How well the RNA polymerase can bind

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10
Q

If there is not access to the promoter… transcription (can/cannot) occur

A

Cannot

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11
Q

How do prokaryotes block access to the promoter?

A

-When a special allosteric protein (repressor protein) binds to a segment of DNA called the operator in front of the gene

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12
Q

How do Eukaryotes block access to the promoter?

A

Controlled by the degree of chromatin condensation

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13
Q

If chromatin is tightly condensed…

A

Access is blocked and there is no transcription

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14
Q

When chromatin is more loosely condensed…

A

Access is open and transcription can occur

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15
Q

The process of opening or tightening the chromatin to allow/ prevent transcription

A

Chromatin Modeling

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16
Q

How is chromatin modeling controlled?

A

Histone and non histone proteins

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17
Q

How do prokaryotes regulate binding strength of RNA polymerase to the promoter and SLOW transcription?

A

-If the repressor is not bound to the operator, only a low level of transcription can occur (constitutive synthesis)

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18
Q

How do prokaryotes regulate binding strength of RNA polymerase to the promoter and INCREASE transcription?

A

-For higher levels of transcription, other proteins must first bind to the promoter (activator proteins)- these promote the binding of RNA polymerase more strongly and result in a higher level of transcription

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19
Q

How do Eukaryotes regulate binding strength of RNA polymerase to the promoter?

A

-If the chromatin is relaxed, the access to the promoter is open

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20
Q

RNA polymerase will only bind to the promoter with the help of proteins called…

A

Transcription Factors

21
Q

-Binding of regulatory repressor protein at DNA regulatory site (operator) inhibits the initiation of transcription

A

Negative Transcriptional Control

22
Q
  • Proteins that exist in active or inactive forms

- Inducers and compressors alter the activity of the repressor by binding

A

Repressor Proteins

23
Q

Type of reaction that we WANT so we add an…

A

Add a inducer, and it is an INDUCIBLE reaction

24
Q

Type of reaction that we don’t want, so we add…

A

Add a corepressor, and it is an REPRESSIBLE reaction

25
Q

If the whole reaction is an inducer, we add a repressor and it… (stops/starts)

A

Stops

26
Q

If the whole reaction is a repressor, we add an inducer and it… (stops/starts)

A

Starts

27
Q

Binding of activator protein at a regulatory region on DNA promotes transcription initiation

A

Positive Transcriptional Control

28
Q

In positive transcriptional control, mRNA synthesis is… (increased/decreased)

A

Increased

29
Q

How is activation turned on or off in Positive Transcriptional Control? (3)

A
  1. Inactive protein is activated by an inducer

2. Active protein is inactivated by an inhibitor

30
Q

Inducable Genes b-Gal Enzyme

A
  • Inducible enzyme functions in a catabolic pathway

- Inducable genes are present only when their substrate(inducer/ effector molecule) is present

31
Q

b-Gal reaction catalyzed is lactose hydrolysis into…

A
  1. Galactose

2. Glucose

32
Q

Enzyme that function in biosynthetic pathways are products of…

A

Repressor Genes

33
Q

Enzymes for repressor genes are always present unless the end product of the biosynthetic pathway is (available/not available)

A

Available

34
Q

Promoter and operator, or activator binding sites, along with functionally related structural genes
-They are grouped together in the DNA

A

Operon

35
Q

In Bacteria and Archaea (monocistronic/polycistronic) mRNA is produced?

A

Polycistronic mRNA

36
Q

Type of Protein that controls the gene expression for all the genes?

A

Regulatory Proteins

37
Q

Lactose (Lac) Operon overview

A

Coding for lactose metabolism or uptake

38
Q

When the lac repressor binds to the operator…

A

Inhibits transcription by blocking access to the promoter for genes

39
Q

Enzymes for Lac Operon aren’t normally produced unless _____ is present

A

Lactose

40
Q

The repressor protein always binds to the…

A

Operator

41
Q
  • Allosteric enzyme that exists in binding form and non binding form
  • Bend DNA and prevent RNA polymerase from accessing promoter
  • Presence of allolactose (inducer) binds receptor
A

Lac Repressor

42
Q

Consists of 5 structural genes with code for enzymes needed to synthesize tryptophan
-Negative transcriptional control of repressible genes by trp repressor indicates that…

A

The operon functions only in the absence of tryptophan

43
Q

Regulation of Gene Expression is Eukarya and Archaea

A

Chromatin Remodeling

44
Q

Lossening of chromatin to allow RNA polymerase access to the promoter

A

Chromatin Remodeling

45
Q

How is chromatin remodeling regulated?

A

By histone and non histone proteins

46
Q

How do Eukaryotes control gene expression?

A

Using regulatory transcription factors to regulate transcription initiation

47
Q

When activators bind enhancers…

A

mRNA transcription increases

48
Q

When repressor proteins bind silencers…

A

mRNA transcription decreases

Microbiology (7 decks)

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