Mutations in the IL2RG gene cause approximately 30 perce...

Question

Mutations in the IL2RG gene cause approximately 30 percent of severe combined immunodeficiency disorder (SCID) cases in humans. These mutations result in alterations to a protein component of cytokine receptors that are essential for proper development of the immune system. The IL2RG gene is composed of eight exons and contains upstream and downstream sequences that are necessary for proper transcription and translation. Below are some of the mutations observed. For each, explain its likely influence on the IL2RG gene product (assume its length to be 375 amino acids).

Missense mutation

Accepted Answer

Hello everyone welcome back. Here's our next question. It says which of the following statements about MS sense mutation is not true. So let's look through our answer choices. Um remembering we want to find the one that is not true. And let's start by recalling what is a mis sense mutation. And a mis sense mutation is simply one where a single base pair is changed in a gene. So with that in mind let's look through our answer choices. Choice A. Says it is a type of point mutation. Well this is true. We're only changing one base pair. That's a point mutation. Just a single change to one base pair in the sequence. So since that's true, choice A. Is not our answer choice choice B says it can cause frame shift mutation. Well let's recall that a frame shift mutation occurs when we have a change in the code on sequence of our gene. So each code on of course codes for amino acid and if we do something that shifts over which three base pairs are included in the code owns. We will have from that point on we'll have completely different amino acids because our whole code on batches have changed and this occurs when you have an insertion or deletion. Um And can shift it over. Imagine we have our you know three say a G. T C. G. A. And then we take out this see if these were our original code ons here. The first three in the second three. Well our second code on is now going to be G. A. And then whatever base pair comes next instead of C. G. A. So that's a frame shift mutation. So this would be false about mis sense mutations. They just substitute one base pair for another. So you're not gonna have any frame shift going on. So this is therefore going to be our answer choice B. It can cause frame shift mutation but we'll keep looking at our other answer choices. Choice C says it can change the structure and function of the resulting amino acid drastically. And this is true depending on what amino acid is being substituted. So if our base pair change causes the code to change to a code for a very different amino acid, maybe we went from a small polar amino acid to a large charged amino acid. That's a big change in the amino acid coded for in that spot. So this is true. This can happen as a result of a mis sense mutation. So that is not our answer and we'll cross that out and then finally, Choice D. It does not significantly change the structure and function of the resulting amino acid. Well, this can also be true. Again, if the substituted amino acid is very similar to the original, they're both small non polar amino acids for example, then that's not a significant change. So either can happen all depending on how that base pair change changes the amino acid that's being coded for. So. Choice D being true. Also not our answer. So again, which of the following statements about mis sense mutations is not true. Choice be It can cause frame shift mutation. See you on the next video.

Key Concepts

IL2RG Gene Function

Types of Mutations

Protein Structure and Function

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