If the sequence T-A-C-C-C-T appears on the informational strand of DNA, what sequence appears opposite it on the template strand? Label your answer with 3′ and 5′ ends.

Question

Accepted Answer

All right. Hello everyone. So this question says that a segment of DNA has the sequence at TGCC on the informational strand, what sequence would be found on the template strand and label the directionality of the DNA strand? So here we have two different, excuse me, four different entry choices labeled A through D. Now options A and C orient the strand from three prime to five prime or as options B and D oriented from five prime to three prime. So for this question, this is going to be in the context of transcription, which is the synthesis of an Mrna from DNA. The first step in transcription is RN a polymerase binding to DNA and unwinding the characteristic double helix of DNA. After unwinding two separate strands are formed, we have the informational strand and the template strand. No recall that DNA in the double stranded form has two strands running in the opposite direction. One of them runs from three prime to five prime and the other runs from five prime to three prime. The informational strand runs from five prime to three prime, whereas the template strand runs from three prime to five prime. So because we're talking about the template strand specifically, we can eliminate options B and D because options B and D orient the strand from five prime to three prime when it's actually the other way around from three prime to five prime. Now, from here, the template strand is what's transcribed during RNA synthesis, MRNA is synthesized on the template strand. However, the tenthly strand is the complement of the informational strand. So essentially the MRN A that's produced from transcription is going to look like the informational strand except uracil replaces thymine whenever it's shown. So now how do you answer a question like this one? Well, we're already given a template, we're already given the informational strand. And what we know is that the informational strand and the template strand are complements of each other. So here, all we would have to do is recall base pairing patterns and DNA Aine compliments vine and cytosine compliments your. So, so for example, if the first base of the informational strand is added in thymine must be the first base in the template strand. So up next, we have thymine, which means adenine complements it, then we have guanine which would complement cytosine. And up next, we have two cyto zines which would each complement guanine followed by a final Adenine complementing thymine and there you have it. So here is our final answer which would be option c in the multiple choice. The template strand runs from three prime to five prime and the sequence is T AC GT. And so with that being said, thank you so very much for watching. And I hope you found this helpful.

If the sequence T-A-C-C-C-T appears on the informational strand of DNA, what sequence appears opposite it on the template strand? Label your answer with 3′ and 5′ ends.

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Key Concepts

DNA Structure

Complementary Base Pairing

Template Strand