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Ch. 17 - Transcriptional Regulation in Eukaryotes
Klug - Concepts of Genetics 12th Edition
Klug12th EditionConcepts of GeneticsISBN: 9780135564776당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Klug 12th EditionCh. 17 - Transcriptional Regulation in Eukaryotes문제 22e
17장, 문제 22e

Explain how the following mutations would affect transcription of the yeast GAL1 gene in the presence of galactose.
A point mutation in the GAL1 core promoter that alters the sequence of the TATA box.

검증된 단계별 안내
1
Understand the role of the TATA box in transcription: The TATA box is a core promoter element that helps position RNA polymerase II and general transcription factors to initiate transcription at the correct site.
Recognize that a point mutation in the TATA box sequence can disrupt the binding affinity of the transcription machinery, potentially reducing or abolishing the recruitment of RNA polymerase II.
Consider that in the presence of galactose, the GAL1 gene is normally activated by specific transcription factors, but if the core promoter is defective, these activators cannot effectively initiate transcription.
Predict that the mutation would likely lead to decreased or no transcription of the GAL1 gene despite the presence of galactose, because the basal transcriptional machinery cannot properly assemble at the promoter.
Summarize that the mutation in the TATA box impairs the fundamental step of transcription initiation, overriding the positive regulatory signals from galactose-induced activators.

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Role of the TATA Box in Transcription Initiation

The TATA box is a core promoter element that helps position RNA polymerase II for accurate transcription initiation. It is recognized by the TATA-binding protein (TBP), which is part of the transcription factor complex. Mutations in the TATA box can disrupt TBP binding, leading to reduced or abolished transcription initiation.
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가이드 코스
10:14
Prokaryotic Transcription

GAL1 Gene Regulation in Yeast

The GAL1 gene in yeast is induced in the presence of galactose and repressed when glucose is available. Its expression depends on the activation of transcription factors that bind upstream regulatory sequences, but proper transcription also requires an intact core promoter, including the TATA box, to recruit the transcription machinery.
추천 영상:
가이드 코스
03:51
GAL Regulation

Effects of Point Mutations on Promoter Function

A point mutation in the promoter region can alter critical DNA sequences necessary for transcription factor binding. In the TATA box, even a single nucleotide change can impair the assembly of the pre-initiation complex, reducing transcription efficiency or completely preventing gene expression despite the presence of activating signals like galactose.
추천 영상:
가이드 코스
09:49
Point Mutations
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교과서 질문

A particular type of anemia in humans, called β-thalassemia, results from a severe reduction or absence of the normal β-globin chain of hemoglobin. However, the γ-globin chain, normally only expressed during fetal development, can functionally substitute for β-globin. A variety of studies have explored the use of the nucleoside 5-azacytidine for the expression of γ-globin in adult patients with β-thalassemia.

How might 5-azacytidine lead to expression of γ-globin in adult patients?

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교과서 질문

Explain how the following mutations would affect transcription of the yeast GAL1 gene in the presence of galactose.

A deletion of one of the four UASG elements upstream from the GAL1 gene.

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교과서 질문

A particular type of anemia in humans, called β-thalassemia, results from a severe reduction or absence of the normal β-globin chain of hemoglobin. However, the γ-globin chain, normally only expressed during fetal development, can functionally substitute for β-globin. A variety of studies have explored the use of the nucleoside 5-azacytidine for the expression of γ-globin in adult patients with β-thalassemia.

Explain why this drug may also have some adverse side effects.

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교과서 질문

Explain how the following mutations would affect transcription of the yeast GAL1 gene in the presence of galactose.

A mutation within the GAL80 gene that blocks the ability of Gal80 protein to interact with Gal3p.

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교과서 질문

Explain how the following mutations would affect transcription of the yeast GAL1 gene in the presence of galactose.

A deletion of the entire GAL3 gene.

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교과서 질문

The interphase nucleus is a highly structured organelle with chromosome territories, interchromatin compartments, and transcription factories. In cultured human cells, researchers have identified approximately 8000 transcription factories per cell, each containing an average of eight tightly associated RNAP II molecules actively transcribing RNA. If each RNAP II molecule is transcribing a different gene, how might such a transcription factory appear? Provide a simple diagram that shows eight different genes being transcribed in a transcription factory and include the promoters, structural genes, and nascent transcripts in your presentation.

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