Question

Imagine that you are studying the control of β-globin gene expression in immature red blood cells (mature red blood cells contain 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 a(n) _____.silencerenhancerpromoterpromoter-proximal elementany of the above

Answer 1

The deleted sequence that increased the rate of transcription in the DNA likely served as a silencer. Silencers are regulatory elements that, once removed, can lift repression on gene expression, resulting in higher transcription levels.

Step-by-step explanation:

The sequence of DNA that you deleted likely functions as a silencer. The role of a silencer is to downregulate the expression of a gene. It does so by providing a binding site for repressor proteins that inhibit transcription. Accordingly, when a silencer is removed, the repression is lifted possibly leading to an increase in the transcription rate of the gene.

Understanding the control of gene expression is critical in eukaryotic cells. Various regulatory elements including enhancers, promoters, and silencers, interact with transcription factors to regulate this process. Enhancers, in contrast to silencers, are DNA sequences that promote transcription through interaction with activator proteins and transcription factors, while promoter regions bind transcription factors to initiate transcription.

Therefore, deleting a silencer could potentially remove an obstruction to gene expression, causing an increase in the rate of transcription of the β-globin gene in immature red blood cells, confirming its repressive role in the regulation of gene expression.

Answer 2

Silencer

Step-by-step explanation:

Silencers are the position and orientation free sequences that are present outside the protein-coding sequence of a gene. Silencers serve as a binding site for some transcriptional regulatory proteins that tend to inhibit gene expression. Binding of these "repressor" proteins to the silencers inhibits the gene expression.

The deletion of silencers from DNA would increase the rate of the gene expression as the inhibitory transcription regulatory proteins do not have binding sites to inhibit the gene expression. Therefore, the deletion of silencer sequences of the beta-globin gene would have caused the increased rate of its expression.