Question

The Eukaryotic enhancer is located 25 bp upstream from the "start" site, binds to the promoter, binds to the TATA consensus region, utilizes DNA "looping" to achieve proper positioning, and acts by blocking the promoter. What is the role of the Eukaryotic enhancer?

1) Activates gene expression
2) Inhibits gene expression
3) Regulates gene expression
4) Stabilizes gene expression

Answer 1

Eukaryotic enhancers are DNA sequences that regulate gene expression by serving as binding sites for activators, which, through interactions with transcription factors and RNA polymerase, can enhance transcription levels.

Step-by-step explanation:

The eukaryotic enhancer is a critical DNA sequence that plays a significant role in the regulation of gene expression. Contrary to the given statement that it acts by blocking the promoter, enhancers typically serve as binding sites for transcription factors, leading to the activation of gene expression. They can be located at various positions relative to the gene they regulate and are involved in DNA "looping" to facilitate the interaction between activators and the transcription machinery at the promoter.

Enhancers bind DNA-bending proteins that change the shape of DNA, allowing for activators to interact with transcription factors, which are attached to promoter regions and RNA polymerase. Despite their varied positions, be it upstream, downstream, within a gene, or thousands of nucleotides away, enhancers can effectively augment transcription levels of a particular gene, depending on whether specific transcription factors are attached to them.