Question

An upstream activator sequence (UAS) can function at variable distances and in either orientation. However, it differs from an enhancer in that it cannot function downstream of the transcription starting point.

A. True
B. False

Answer 1

The statement that an upstream activator sequence cannot function downstream of the transcription starting point is false; enhancers, which are similar to UAS, can function in various positions relative to the gene.

Step-by-step explanation:

The statement in the question regarding upstream activator sequences (UAS) suggests that a UAS differs from an enhancer because it cannot function downstream of the transcription starting point. This is false. In reality, enhancers can function upstream, downstream, within a coding region, or even thousands of nucleotides away from the gene they regulate. They are capable of promoting transcription due to their ability to fold DNA such that they come into proximity with the promoter region, subsequently interacting with the transcription initiation complex.