Imagine that you are studying the control of β-globin gene expression in immature red blood cells. (Mature red blood cells conta
in β-globin protein but lack a nucleus and, therefore, the β-globin gene.) If you deleted a sequence of DNA outside the protein-coding region of the β-globin gene and found that this increased the rate of transcription, the deleted sequence likely functions as ________.
Gene expression is regulated by many upstream and downstream regulatory sequences. A regulatory site may serve as a binding site for positive or negative transcription factors to regulate gene expression. A regulatory site that binds negative regulators/ transcription factors to control transcription is called a silencer.
In the given example, the deletion of a DNA sequence outside the protein-coding region of the beta-globin gene resulted in an increased rate of expression. This means that the deleted sequence was a silencer and served to inhibit the expression of the beta-globin gene.
The longest day of the year isn't the hottest day of the year because the phenomenon of the hottest weather following the summer solstice by a month or two is called the lag of seasons.
