In the experiments that deciphered the genetic code, many diff...

Question

In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.

What result was obtained for synthetic mRNAs containing AG repeats, that is, AGAGAGAG...?

Accepted Answer

Hi, everyone. Let's look at our next problem. The genetic codes for the different amino acids are given as follows. U A U tyrosine C A U histidine, C C C Prolene, U U U, Venny Alanine. What will be the possible sequence of M R N A for the following oligopeptide, tyrosine histidine, Prolene, Beno Alanine. And our answer choices are a five prime A U G U A U C A U C C C U U U U G A three prime B five prime U G A U A U C A U C C C U U U U G A three prime, C five prime U G A U A U C A U C C C U U U A U G three prime N D five prime U G A A U G U A U C A U C C C U U U three prime. So we have our amino acid sequence. So first we want to find the codons for each amino acid. But then we'll also want to remember if we're looking for a sequence of M R N A to uh specify a single oligo peptide. We'll want to add a start coat on at the beginning and a stop code on at the end. So we'll start with our codons for the amino acids. We've got tyrosine and we see that, that codon is U A U as is given to us in the problem histamine, which is C A U prolene, our problem and C C C C and finally, phenylalanine just you, you, you. So now we have our uh coding region for the amino acids. We need the start codon and the start codon is a U G. That's something just to no here and stop codon. We have three different possibilities. I write them off here. And when we look at our answer choice, we can find the one that's there and a fun and common way to remember the stop codons as you think of an annoying person. Do you want them to stop being near you? And the codons are, you are annoying. U A A, you are gone U A G and you go away U G A just a helpful way uh to remember the three stop code on possibilities. So let's go on over to our answer choices and look for the sequence that corresponds to what we figured out. So we need to start with a U G. And actually, that makes our choice very easy because we only have a single sequence here that starts with U A U G and that's choice A. So all of our other answer choices start with something else. Choice B starts with U G A choice C starts with U G A and choice D starts with U G A. So all three of those have a stop code on in the beginning and therefore aren't correct. So we can just to be thorough, double check that we're correct here. And we have a U G R start code on U A U R tyrosine C A U histidine, C C C Prolene, U U U pyla. And then the stop code on U G A. One of our three choices. So choice A is indeed our possible sequence of M R N A for the oligo peptide we were given in this problem. See you in the next video.

In the experiments that deciphered the genetic code, many different synthetic mRNA sequences were tested.
What result was obtained for synthetic mRNAs containing AG repeats, that is, AGAGAGAG...?

Key Concepts

Genetic Code

mRNA and Translation

Repetitive Sequences and Codon Bias

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