Assume all the necessary general and regulatory transcriptio

Assume all the necessary general and regulatory transcription factors are available and active,
If we are assessing transcription of two genes, one containing a promoter and a silencer and the second contains only a promoter, which of the two will be transcribed more efficiently?

a) Gene 1

b) Gene 2

c) Both genes would be efficiently transcribed

d) Neither gene would be efficiently transcribe

Solution

Gene 1 will be transcribed more efficiently

In 1985, elements were discovered in yeast, which mediated repression and therefore were called silencers. Like enhancer, a silencer also functions irrespective of its position (upto 2.5kb away) and orientation relative to the gene, whose expression it controls. Silencer sequences have also been reported for HIV and called negative response element and also for chicken lysozyme gene. The silencer factor (a protein) either locks the transcription initiation complex and makes it unavailable for activating factors or it disorganizes the transcription initiation complex.