The DNA sequence below gives the first 12 base pairs of ...

Question

The DNA sequence below gives the first 12 base pairs of the transcribed region of a gene, and the template and nontemplate strands of DNA are identified. The transcription start is the thymine nucleotide at the end of the sequence given. Use the diagram to answer the list of questions. Make a copy of the diagram before you begin answering the questions, or have one group member diagram the answers for bacteria and another group member diagram the answers for eukaryotes.

Nontemplate strand ___________TTGCTACGGTCA___________
Template strand ___________AACGATGCCAGT___________

Assuming the sequence shown is part of a eukaryotic gene, what consensus sequence(s) would you expect to identify within about 100 base pairs of the start of transcription?

Accepted Answer

Welcome back, everyone. Here's our next question. Which consensus sequence or sequences would you expect to identify within about 100 base pairs of the start of transcription for a U Caro gene with the following DNA sequence, non template strand A T G C T AC G G T C A template strand T AC G A T G C C A G T. And our answer choices are a tata box or T A T A box, choice B cat box or CAA T box, choice C G C box or choice D, all of the above. So with that in mind that we have that answer choice, all of the above. So we might have more than one correct answer. Let's think this through. Well, this is an example of a question that gives us some extraneous information. We don't actually need to know what our DNA sequence of our gene is. It doesn't matter. We're talking about a eukaryotic gene and looking for consensus sequences that occur about 100 base pairs upstream of the start of transcription. So there are some really common consensus sequences in you Rios. And let's look through our answer choices here we have choice A, the tata box, T A T A box. And this is indeed a very common consensus sequence found before the site of transcription. The tata box tends to be about 25 to 30 base pairs upstream. So quite close to the start of transcription and is commonly found in eucaryotic genes. I've marked it with a little dot Because again, we have that option all of the above. So we may have more than one correct answer. Then choice B the cat box or CAA T box. This is also a very common consensus sequence. It's usually accompanied by another one of the consensus sequences um involved in gene regulation. Uh You've probably heard about uh cat box binding proteins that affect the transcription of genes and the cat box proteins are usually found between 60 to 100 base pairs upstream. So again, we're within that range that our question identifies, asking us what we'd expect to identify within about 100 base pairs of the start of transcription. So we can choose B as also being incorrect. Well, if I'm in a hurry, I'm on a test, I'm going to go ahead and select D all of the above is my answer here. I've already got more than one correct answer. I could pick that and move on. But in the interest of being thorough, we will look at choice C which is the G C box. And yes, this is also commonly found in you upstream of the starter transcription and new Caro genes. And it's usually found between 38 to 32 base pairs upstream. So again, within our window that we're looking at, so which consensus sequences would we expect to identify within about 100 base pairs at the start of transcription for a U Caro gene? With the following DNA sequence choice D all of the above. See you in the next video.

Key Concepts

Transcription in Eukaryotes

Consensus Sequences

Template and Nontemplate Strands

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