In this chapter, we focused on how eukaryotic genes are regulated at the transcriptional level. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, How do we know that the orientation of promoters relative to the transcription start site is important while enhancers are orientation independent?

Video transcript

Hi everyone. Let's take a look at this practice problem together, enhancers are binding sequences that can be located thousands of nucleotides away from the gene. How do they enhance the transcription process. So physically they are very far away from the start of transcription. So how is it that they are enhancing it? And we are told that they are D. N. A sequences and that they are binding. So let's take a look at our options. A. They directly initiate the transcription process. Now recall that it's when a transcription factor binds with RNA polymerase. That is what initiates transcription. So A is not correct. Then we have B. They release RNA polymerase. Well if they did this there would be no transcription occurring since transcription is done by the RNA preliminaries. And so B is not correct. Then we have C. They believed the D. N. A. Gap so they can be relocated near the promoter site. Well we are told that they are binding and this says cleaving which those two are basically the opposite of each other. And if they did this they would probably be cleaving off whole sections of DNA that would most likely need to be transcribed. And so C. Is also incorrect. Then we've got D. They bind to transcription factors called activators. Now this is the correct answer. And when they do this it literally changes the shape of the D. N. A. And it forms loops so that the D. N. A. Loops around and the enhancer can then be physically near the promoter region of the gene which it helps to initiate or enhance the transcription process. Sorry, answer is D. All right, everyone. I hope you found this helpful, and I'll see you soon for the next practice problem.