key term - Enhancer

Definition

An enhancer is a regulatory DNA sequence that can significantly increase the transcription of specific genes. These elements work by binding to transcription factors, which then interact with the core promoter and other proteins to facilitate the assembly of the transcription machinery. Enhancers play a critical role in gene expression regulation by controlling when and where specific genes are activated in eukaryotic cells.

5 Must Know Facts For Your Next Test

1. Enhancers can function at considerable distances from the genes they regulate, sometimes located thousands of base pairs away.
2. They can be found in introns, exons, or even in non-coding regions of the genome.
3. The activity of enhancers is influenced by various factors, including the presence of specific transcription factors and the chromatin state around them.
4. Enhancers are often tissue-specific, meaning they may only activate certain genes in particular cell types or developmental stages.
5. Mutations in enhancer regions can lead to misregulation of gene expression, potentially contributing to diseases such as cancer.

Review Questions

• How do enhancers interact with transcription factors and what role do they play in regulating gene expression?
  • Enhancers interact with transcription factors by providing binding sites that facilitate these proteins' attachment to DNA. When transcription factors bind to enhancers, they can then recruit additional proteins and form a complex that interacts with the core promoter of a gene. This interaction enhances the likelihood that RNA polymerase will transcribe the associated gene, thereby regulating its expression more effectively. Without enhancers, many genes would not be expressed at appropriate levels or times.
• Compare and contrast the functions of enhancers and silencers in gene regulation.
  • Enhancers and silencers both act as regulatory elements but serve opposite functions in gene regulation. Enhancers promote and enhance transcription when bound by specific transcription factors, leading to increased gene expression. In contrast, silencers inhibit transcription by attracting repressive proteins that prevent the assembly of the transcription machinery at the promoter. Together, these elements provide a finely tuned control system for gene expression, allowing cells to respond to internal and external signals appropriately.
• Evaluate the implications of enhancer mutations on human health, particularly in relation to genetic diseases.
  • Mutations in enhancer regions can have significant implications for human health by disrupting normal patterns of gene expression. These mutations may lead to either overexpression or underexpression of critical genes involved in processes like cell growth and differentiation. For instance, misregulation of oncogenes or tumor suppressor genes due to enhancer mutations can contribute to the development of cancers. Understanding how these mutations affect enhancer function provides insight into potential therapeutic targets and strategies for managing genetic diseases.

Related terms

Promoter:

A DNA sequence located upstream of a gene that serves as the binding site for RNA polymerase and initiates transcription.

Transcription Factors: Proteins that bind to specific DNA sequences, such as enhancers and promoters, to regulate the transcription of genes.

Silencer:

A DNA sequence that can inhibit the transcription of a gene, functioning oppositely to enhancers.