A 3-year-old child exhibited some early indication of Turner syndrome, which results from a 45,X chromosome composition. Karyotypic analysis demonstrated two cell types: 46,XX (normal) and 45,X. Propose a mechanism for the origin of this mosaicism.

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Hello, everyone. Welcome back. Let's look at our next problem. It says mosaic Turner syndrome happens when some of the individual's body cells have a pair of X chromosomes. While the other body cells I have only one. Hence, moses is um maybe caused by an error during. And let's look at our answer choices. We've got mitosis, mitosis Permata, genesis and O genesis. Well, the key here we want to focus on whenever we have moses is um as a question says, not all somatic cells have the mutation. So again, in Turner Syndrome, that's when the individual, if the person is not mosaic, if they have Turner Syndrome, that's the condition when there's only one X chromosome and individuals missing the other X chromosome. But now we're saying mosaic Turner syndrome, some of the body cells are missing the second X, but some of them have two X chromosomes. So when we think about it, how would that happen? Well, it has to mean that the mutation occurred after fertilization if the mutation has occurred in the gametes, um all of the body cells would have that mutation. But after fertilization and early embryonic development, if you just have that mutation arise. And one of the cells, then you'd have all the daughter cells of that one with that missing x chromosome. While daughter cells of all the other cells in that early embryo would be normal. So when we think about after fertilization, early embryonic development, the process we're thinking about is mitosis, that's the process of cell division and then um differentiation growth development. So when we look at our answer choices, we see choice be mitosis is going to be what we're looking for. Because when we look at all the other answer, choices, mitosis is that you know, cell division that forms the gametes ends up resulting in those half Floyd daughter cells and then sperm a genesis and oh genesis, of course, those process processes that lead to the formation of sperm and eggs, the gametes. So again, if that mutation occurs in the sperm or in the egg, the resulting individual would have Turner syndrome in all of their cells. So choice B mitosis is what would cause moses is um most likely since that would be the only thing that would result in some of the individual cells having the mutation while some did not see you in the next video.

A 3-year-old child exhibited some early indication of Turner syndrome, which results from a 45,X chromosome composition. Karyotypic analysis demonstrated two cell types: 46,XX (normal) and 45,X. Propose a mechanism for the origin of this mosaicism.

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Key Concepts

Turner Syndrome and Chromosomal Composition

Mosaicism in Genetics

Mechanisms of Chromosomal Nondisjunction and Anaphase Lag