Assuming the genetic code is a triplet, what effect would the ...

Question

Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? The addition or loss of three, six, or nine nucleotides?

Accepted Answer

Hi everyone. Let's take a look at this practice problem together determine the polyp peptide that the following strand of M. RNA specifies in humans and here's our M. RNA strand. So a polyp peptide is a string of amino acids bonded together. So this question is asking us to translate this M. RNA strand and we do that using code ins recall that every three nucleotides is one coat on and one coat on produces one amino acid. And also recall that there's only one start code on for all of em RNA that tells us where to begin translation and that start code on is always a U. G. Now for our strand that were given that's right at the beginning. So we're going to begin translation there. So let's write our M. RNA strand first identifying the code ons. So we have five prime A U. G. And I'll cross them off as we go. Then we have a G G. Another a G g a U A A U G U G. G. And lastly we have you you you so we have a total of seven code ons. Now how do we get from the code ons to the amino acids. You should recall that. You're going to have to use something called a genetic code table. Let me go ahead and copy and paste that into here. Um so how we read this is our first column is our first nucleotide in our code on the top row is your second nucleotide and your third nucleotide is represented by this column. So for example A U. G. We're going to identify it here's the A. Is our first nucleotide, you is our second nucleotide. And our third nucleotide is G. So a U. G. Is the start code on it is always M E. T. Which is the amino acid matthias. Mean next we'll look at A G. So again we have a G. G. So A G will code for A R. G. Which is the amino acid arginine. We have another A. G. So it will also encode for arginine. Next we have a U. A. So a U A will be right there for I solution is I L E. Then we have another A U. G. Which is M E T followed by U G G. So you G G. So that's going to be trp which is tryptophan. And lastly we have you you you so you you and you which is going to be the amino acid P H E. Which is fennel reality. You're not expected in this question to know what the abbreviated amino acids are. I just know them from many years of practice. Um So that's how I'm able to translate them for you. But the most important part for you is to be able to identify them here in the table and know the abbreviation. So now this is our polyp peptide. So all we have to do is identify the correct answer. So our correct answer is D. So I hope when you see a problem like this, you realize that you're going to need this genetic code table. You won't get very far in the question without it. Um, so I hope you found this helpful and I'll see you guys soon for the next practice problem.

Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? The addition or loss of three, six, or nine nucleotides?

Key Concepts

Reading Frame

Frameshift Mutation

Codon and Genetic Code

Watch next