Question

Imagine that you've discovered a regulatory sequence thousands of base pairs away from the promoter and that when this sequence is lost due to mutation, levels of gene expression decrease sharply. This sequence is most likely ______.
A. A silencerB. An enhancerC. A promoter-proximal elementD. A promoter

Answer 1

Answer:

An Enhancer

Explanation:

Enhancers are the regulatory sequences and are generally located 80-160 base pairs upstream of the transcription start site. Enhancers have bidirectional elements that are involved in the initiation of transcription. Enhancers serve as the binding sites for activators to increase the concentration of activators in the vicinity of the promoter and thereby increase the rate of transcription of the gene.

According to the given information, the loss of a regulatory sequence led to a reduced level of transcription of the gene. This means that the regulatory sequence was involved in the upregulation of transcription. The presence of the sequence far away from the promoter makes it an enhancer.