Genetics #3 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
If the whole reaction is an inducer, we add a repressor and it... (stops/starts)
Stops
26
If the whole reaction is a repressor, we add an inducer and it... (stops/starts)
Starts
27
Binding of activator protein at a regulatory region on DNA promotes transcription initiation
Positive Transcriptional Control
28
In positive transcriptional control, mRNA synthesis is... (increased/decreased)
Increased
29
How is activation turned on or off in Positive Transcriptional Control? (3)
1. Inactive protein is activated by an inducer | 2. Active protein is inactivated by an inhibitor
30
Inducable Genes b-Gal Enzyme
- Inducible enzyme functions in a catabolic pathway | - Inducable genes are present only when their substrate(inducer/ effector molecule) is present
31
b-Gal reaction catalyzed is lactose hydrolysis into...
1. Galactose | 2. Glucose
32
Enzyme that function in biosynthetic pathways are products of...
Repressor Genes
33
Enzymes for repressor genes are always present unless the end product of the biosynthetic pathway is (available/not available)
Available
34
Promoter and operator, or activator binding sites, along with functionally related structural genes -They are grouped together in the DNA
Operon
35
In Bacteria and Archaea (monocistronic/polycistronic) mRNA is produced?
Polycistronic mRNA
36
Type of Protein that controls the gene expression for all the genes?
Regulatory Proteins
37
Lactose (Lac) Operon overview
Coding for lactose metabolism or uptake
38
When the lac repressor binds to the operator...
Inhibits transcription by blocking access to the promoter for genes
39
Enzymes for Lac Operon aren't normally produced unless _____ is present
Lactose
40
The repressor protein always binds to the...
Operator
41
- 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
Lac Repressor
42
Consists of 5 structural genes with code for enzymes needed to synthesize tryptophan -Negative transcriptional control of repressible genes by trp repressor indicates that...
The operon functions only in the absence of tryptophan
43
Regulation of Gene Expression is Eukarya and Archaea
Chromatin Remodeling
44
Lossening of chromatin to allow RNA polymerase access to the promoter
Chromatin Remodeling
45
How is chromatin remodeling regulated?
By histone and non histone proteins
46
How do Eukaryotes control gene expression?
Using regulatory transcription factors to regulate transcription initiation
47
When activators bind enhancers...
mRNA transcription increases
48
When repressor proteins bind silencers...
mRNA transcription decreases