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Questions and Answers
What type of proteins are common to all cells of a multicellular organism?
What type of proteins are common to all cells of a multicellular organism?
Why is it more efficient to turn on genes when they are required?
Why is it more efficient to turn on genes when they are required?
What enables a cell to change the expression of its genes in response to external signals?
What enables a cell to change the expression of its genes in response to external signals?
Where do regulatory sequences that transcription factors bind to vary in length?
Where do regulatory sequences that transcription factors bind to vary in length?
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What happens in negative regulation through transcription factors?
What happens in negative regulation through transcription factors?
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What can remove a repressor protein from the promoter region to enable transcription by RNA polymerase?
What can remove a repressor protein from the promoter region to enable transcription by RNA polymerase?
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Which type of regulation happens through transcription factors?
Which type of regulation happens through transcription factors?
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What happens when the repressor undergoes a conformational change due to ligand binding?
What happens when the repressor undergoes a conformational change due to ligand binding?
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What is the role of activators in gene transcription?
What is the role of activators in gene transcription?
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What is an operon in prokaryotes?
What is an operon in prokaryotes?
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What is the function of Lac Y in the lactose operon?
What is the function of Lac Y in the lactose operon?
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How does the presence of glucose affect the binding of CRP/CAP to the lac operon?
How does the presence of glucose affect the binding of CRP/CAP to the lac operon?
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What is the function of the trp repressor in the trp operon?
What is the function of the trp repressor in the trp operon?
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What happens when tryptophan acts as a co-repressor in the trp operon?
What happens when tryptophan acts as a co-repressor in the trp operon?
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How are eukaryotic regulatory mechanisms different from prokaryotic operons?
How are eukaryotic regulatory mechanisms different from prokaryotic operons?
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True or false: The repressor undergoes a conformational change when ligands bind and is no longer able to bind to DNA promoter regions, allowing gene transcription to occur?
True or false: The repressor undergoes a conformational change when ligands bind and is no longer able to bind to DNA promoter regions, allowing gene transcription to occur?
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True or false: Activators stops gene transcription by binding to DNA regulatory sequences and recruiting RNA polymerase for transcription?
True or false: Activators stops gene transcription by binding to DNA regulatory sequences and recruiting RNA polymerase for transcription?
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True or false: The lactose operon consists of four important genes: Lac Y, Lac Z, Lac A, and Lac B?
True or false: The lactose operon consists of four important genes: Lac Y, Lac Z, Lac A, and Lac B?
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True or false: The trp operon is positively regulated by the trp repressor, which binds to the operator sequence in the absence of tryptophan, preventing transcription?
True or false: The trp operon is positively regulated by the trp repressor, which binds to the operator sequence in the absence of tryptophan, preventing transcription?
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True or false: Eukaryotic regulatory mechanisms involve fewer repressors and activators compared to prokaryotic operons?
True or false: Eukaryotic regulatory mechanisms involve fewer repressors and activators compared to prokaryotic operons?
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Study Notes
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The repressor can bind to DNA promoter regions on its own, but when ligands bind, it undergoes a conformational change and is no longer able to bind, causing gene transcription to occur.
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Activators bind to DNA regulatory sequences and recruit RNA polymerase for transcription, but ligand binding can hinder their ability to bind and thereby block gene transcription.
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An operon is a group of genes in prokaryotes that function as a single transcription unit, including an operator, promoter, and structural genes.
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The lactose operon, for example, consists of three important genes: Lac Y, responsible for lactose uptake; Lac Z, responsible for lactose hydrolysis; and Lac A, of unknown function.
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In the absence of lactose, the repressor binds to the operator region to inhibit transcription. When lactose is present, it acts as a ligand and causes a conformational change in the repressor, preventing it from binding to the operator and allowing transcription to occur.
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The lac operon is regulated by both the repressor and the transcription activators cAMP receptor protein (CRP) and catabolite activator protein (CAP).
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The presence of glucose, a preferred carbon source, keeps cAMP levels low, preventing CRP/CAP from binding and initiating transcription of the lac operon.
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The trp operon, which encodes genes for tryptophan biosynthesis, is negatively regulated by the trp repressor, which binds to the operator sequence in the absence of tryptophan, preventing transcription.
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In the presence of tryptophan, it acts as a co-repressor and binds to the trp repressor, causing it to bind to the operator and prevent RNA polymerase from binding, thereby blocking transcription.
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Eukaryotes have more complex regulatory mechanisms involving multiple repressors and activators, as well as individual gene transcription rather than operons.
-
The repressor can bind to DNA promoter regions on its own, but when ligands bind, it undergoes a conformational change and is no longer able to bind, causing gene transcription to occur.
-
Activators bind to DNA regulatory sequences and recruit RNA polymerase for transcription, but ligand binding can hinder their ability to bind and thereby block gene transcription.
-
An operon is a group of genes in prokaryotes that function as a single transcription unit, including an operator, promoter, and structural genes.
-
The lactose operon, for example, consists of three important genes: Lac Y, responsible for lactose uptake; Lac Z, responsible for lactose hydrolysis; and Lac A, of unknown function.
-
In the absence of lactose, the repressor binds to the operator region to inhibit transcription. When lactose is present, it acts as a ligand and causes a conformational change in the repressor, preventing it from binding to the operator and allowing transcription to occur.
-
The lac operon is regulated by both the repressor and the transcription activators cAMP receptor protein (CRP) and catabolite activator protein (CAP).
-
The presence of glucose, a preferred carbon source, keeps cAMP levels low, preventing CRP/CAP from binding and initiating transcription of the lac operon.
-
The trp operon, which encodes genes for tryptophan biosynthesis, is negatively regulated by the trp repressor, which binds to the operator sequence in the absence of tryptophan, preventing transcription.
-
In the presence of tryptophan, it acts as a co-repressor and binds to the trp repressor, causing it to bind to the operator and prevent RNA polymerase from binding, thereby blocking transcription.
-
Eukaryotes have more complex regulatory mechanisms involving multiple repressors and activators, as well as individual gene transcription rather than operons.
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Description
Test your knowledge on gene expression and cell specialization in organisms. Explore how housekeeping proteins and specialized proteins contribute to the distinctive properties of different cell types.
