Family trees - X,Y chromosomes - Contenido educativo
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The family trees used in the video were obtained from the following webpages:
- https://migrc.org/teaching-tools/genetic-inheritance-patterns/sexx-linked-dominant/
- https://migrc.org/teaching-tools/genetic-inheritance-patterns/sexx-linked-recessive/
- https://www.mun.ca/biology/scarr/Y-linked_inheritance.html
- https://migrc.org/teaching-tools/genetic-inheritance-patterns/sexx-linked-dominant/
- https://migrc.org/teaching-tools/genetic-inheritance-patterns/sexx-linked-recessive/
- https://www.mun.ca/biology/scarr/Y-linked_inheritance.html
In this video we are going to analyze how to solve the problems in which we have family trees
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representing the inheritance of a trait that is determined by a gene located in the sex chromosome
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in the x or in the y chromosome that are the pair 23. So the easiest thing is to analyze if this
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trait is y linked because the chromosome y is only present in men then analyze the squares
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the squares of the tree okay if there are only squares color in black this means that only men
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are affected by this disease or only men can have can show this trait and no circle is is color in
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black so there is no possibility of a woman showing this trait this means that the gene
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the trait that we are analyzing is located in the y chromosome this is the case okay you can see that
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All these squares are colored in black, all these squares are having the trait, but not the circles, no circles having the trait.
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There are some squares, like this individual that is 2-7, that is not showing the trait, but it's okay because he is from a different family.
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I mean, if you take this man that is having the trait because the square is colored in black, all his sons should also be colored in black, okay?
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But this guy is not a son of individual 1-4, so that is not a problem.
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for this man
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one one that is also
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coloring black that he is
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showing the trait
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he has only one son
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that is also coloring black
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so he also has the trait
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and this individual that is
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two two is
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having two sons
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that also are coloring black
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so everything fits
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this tree is representing
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the inheritance of a
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trait
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That is Y-linked.
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If woman, if any woman is affected, I mean, by the disease or is having the tree, then the trait is going to be X-linked.
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In this case, we can see circles that represent women that are colored in black.
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So this means that is an X-linked trait.
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Okay, now that we know that it's an X-linked trait, it can be both recessive or dominant.
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So, if the trait is recessive, all the sons of a woman, like this one, that has the trait that is colored in black,
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All the sons, man, are going also to show the trait.
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So all the squares, the men, that are sons from a woman that is coloring black, that has the trait, should be also coloring black.
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So the sons, boys, look at this individual 13 or individual 15.
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These boys that are sons of a woman with the trait also have the trait.
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And the same for five and seven.
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They are sons of a woman with the trait and they also have the trait.
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This means that the trait is recessive.
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If we have a woman that has the trait with a son that doesn't have the trait, then it should be dominant.
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This is the case.
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Over here, you have a woman with the trait that has one son also with the trait, but one son without the trait.
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This means that the trait should be X-linked and dominant.
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If it were recessive, both sons of this woman should show the trait.
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And for being sure that the trait is dominant, we are going to analyze the daughters of a man with the trait.
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Because if the disease or the trait is X-linked and it is dominant, a man that is having the disease is going to carry the X chromosome with the dominant allele.
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And this X chromosome is going to be netted by all his daughters.
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So if all the daughters, in this case 8 and 10, of a man, 7, that has the trait or the disease,
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they are going to also have the trait or the disease if this is dominant.
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OK, so for this type of exercises, you need to analyze the sons squares from a woman circle that has the trait.
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So you look for a black circle and analyze the squares that represent her sons and also the daughters, the circles of a man, a square that is also colored in black.
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Okay, so if all the sons of a woman with the trait have also the trait, it is going to be recessive.
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If the woman with the trait has at least one son without the trait, it is dominant.
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And the other way around, if all the daughters of a man with the trait also have the trait, it is going to be dominant.
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But if a man with the trait has at least one daughter without it, it is going to be recessive.
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- Materias:
- Biología
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Educación Secundaria Obligatoria
- Ordinaria
- Segundo Ciclo
- Cuarto Curso
- Ordinaria
- Subido por:
- Tania M.
- Licencia:
- Todos los derechos reservados
- Visualizaciones:
- 1
- Fecha:
- 21 de abril de 2026 - 22:33
- Visibilidad:
- Clave
- Centro:
- IES SAN JUAN BAUTISTA
- Duración:
- 07′ 02″
- Relación de aspecto:
- 1.89:1
- Resolución:
- 1520x804 píxeles
- Tamaño:
- 13.06 MBytes
