Predict the amino acid sequence produced during translat...

Question

Predict the amino acid sequence produced during translation by the following short hypothetical mRNA sequences (note that the second sequence was formed from the first by a deletion of only one nucleotide):

Sequence 1: 5'-AUGCCGGAUUAUAGUUGA-3'
Sequence 2: 5'-AUGCCGGAUUAAGUUGA-3'

What type of mutation gave rise to sequence 2?

Accepted Answer

Hello everyone Here's our next problem when there is an accidental edition of a single nitrogen base in A. D. N. A sequence it can cause, well let's just draw a little diagram to think through what's happening here. So we've only got a single base being added. However let's imagine here. So here's our D. N. A sequence. Now let's imagine that we come along and we insert a. T. So just a single base and we insert it here in the third position. Well now our D. N. A sequence it's only been changed by one. We just have this one additional base here. However when we look at the code owns and the amino acids are going to code for and originally we had our code owns like this A G A C P A G C. P by inserting an extra base. We've thrown off all of our code ons here. So now instead of a G. A we have A G T. C. Ta becomes a C T G C T. Is a G C. So going forward all along most of our code ons are gonna code for different amino acids and they did originally. So you're going to change the entire amino acid sequence of the protein most likely after the insertion. So with that in mind let's look at our answer choices, choice A says point mutation. A point mutation would be a substitution. So when we substitute a single base for the wrong one. So that's much less likely to have a huge effect because it'll affect just the code on its in now depending on your base. If your basis um leads to coding for very different amino acid, it could have large effects, as in sickle cell anemia on the structure of the protein it's coding for. But in general you're less likely to see a big effect than insertion which causes this whole shifting of all the code ins so choice isn't correct. Choice B is frame shift mutation. And that is what we see here because it alters the reading frame after that insertion all the coders are going to be thrown off by shifting everything over by one. Choice C. Says duplication. That's not what's happening here. We're not duplicating a portion of the sequence and seeing it repeated twice, just inserting a single base pair. And then finally Choice D non deleterious mutation. It's very unlikely that a frame shift mutation like this would be not deleterious since as I said, that changes every single amino acid in the protein after your frame shift. So that would be very unlikely not to be a deleterious effect. So again, an accidental edition of a single nitrogen base in a DNA sequence can cause Choice B frame shift mutation. See you in the next video

Key Concepts

Translation

Mutations

Frameshift Mutation

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