Summary
Distant regulatory DNA elements that increase or decrease transcription via looping to the promoter.
In depth
Enhancers can be thousands of base pairs from the gene and act in either orientation. DNA looping brings bound activators to the promoter through Mediator. Tissue-specific enhancers allow genes to be used in different places at different times.
Mutations in enhancers cause disease, such as limb malformations.
Enhancers are typically 100 to 1000 base pairs and carry binding sites for several factors; the human genome has hundreds of thousands. A gene may have several enhancers with different tissue patterns, as for the Sonic hedgehog limb enhancer ZRS, located about a million base pairs from the gene: mutations there cause extra fingers (polydactyly).
Insulators or boundary elements prevent enhancers from acting on the wrong genes, often bound by CTCF within TADs. Super-enhancers, clusters of enhancers, define cell identity and are often co-opted in cancer. CRISPR screens and chromosome conformation capture help to link enhancers to targets.
Frequently asked questions
What is Enhancers and Silencers?
Distant regulatory DNA elements that increase or decrease transcription via looping to the promoter.
Which area of biology covers Enhancers and Silencers, and how advanced is it?
Enhancers and Silencers is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Chromosome Territories, Transcription Factors, Alternative Splicing.
Why does Enhancers and Silencers matter?
Most disease-associated variants from GWAS lie in non-coding regions, many in enhancers.
Can you give an example of Enhancers and Silencers?
A limb enhancer of the Shh gene lies about a million base pairs away.
What should I learn before Enhancers and Silencers?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Enhancers and Silencers. Intermediate topics assume the Beginner vocabulary.
What topics are related to Enhancers and Silencers?
The closest topics to Enhancers and Silencers are Chromosome Territories, Transcription Factors, Alternative Splicing, Mediator Complex. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Enhancers and Silencers?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Enhancers and Silencers. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is Enhancers and Silencers different from Chromosome Territories?
Enhancers and Silencers: Distant regulatory DNA elements that increase or decrease transcription via looping to the promoter. Chromosome Territories: Individual chromosomes occupy distinct regions of the nucleus, influencing genome organisation and expression. Read both side by side and note what each one explains.
How should I study Enhancers and Silencers step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Chromosome Territories and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.