Textbook Question
What are the different chromatin classifications, and what is their relationship to gene expression?
529
views
13. Gene Regulation in Eukaryotes
Epigenetics, Chromatin Modifications, and Regulation
1:55 minutesProblem 13
Textbook Question
Describe the manner in which activators and repressors influence the rate of transcription initiation. How might chromatin structure be involved in such regulation?
Verified step by step guidance1
Begin by defining activators and repressors: Activators are proteins that increase the rate of transcription initiation by facilitating the binding of RNA polymerase to the promoter, while repressors decrease transcription by hindering this process.
Explain how activators function: Activators typically bind to specific DNA sequences called enhancers or upstream activating sequences, promoting the assembly of the transcriptional machinery and stabilizing RNA polymerase at the promoter.
Describe the role of repressors: Repressors bind to operator regions or silencers near the promoter, blocking RNA polymerase binding or recruiting other proteins that inhibit transcription initiation.
Introduce chromatin structure: Chromatin is composed of DNA wrapped around histone proteins, forming nucleosomes that can either compact or relax DNA accessibility.
Explain how chromatin structure influences regulation: Activators can recruit chromatin remodeling complexes or histone-modifying enzymes to open up chromatin, making DNA accessible for transcription, whereas repressors can promote chromatin condensation, making the DNA less accessible and thus reducing transcription initiation.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Role of Activators and Repressors in Transcription
Activators are proteins that increase transcription by binding to specific DNA sequences and facilitating the recruitment of RNA polymerase and transcription machinery. Repressors, conversely, bind to DNA to block or hinder the assembly of these components, reducing transcription initiation. Their interaction with promoter or enhancer regions directly influences gene expression levels.
Recommended video:
Guided course
09:16
Eukaryotic Transcription
Transcription Initiation Mechanism
Transcription initiation involves the assembly of RNA polymerase and general transcription factors at the promoter region of a gene. This process is tightly regulated by regulatory proteins like activators and repressors, which modulate the accessibility and efficiency of the transcriptional machinery to start RNA synthesis.
Recommended video:
Guided course
09:16Eukaryotic Transcription
Chromatin Structure and Gene Regulation
Chromatin structure affects gene expression by controlling DNA accessibility. Tightly packed chromatin (heterochromatin) restricts transcription factor binding, while loosely packed chromatin (euchromatin) allows easier access. Activators and repressors can influence chromatin remodeling, thereby modulating transcription initiation indirectly through changes in chromatin state.
Recommended video:
Guided course
04:35Chromatin
Related Videos
Related Practice