Mrs. Eryth is carrier of the sex-linked hemophilia allele (XAXa) and Mr. Eryth is normal (XAY). Draw a Punnett square that shows the theoretical genotypes and phenotypes among their children.
To draw a Punnett square and understand the theoretical genotypes and phenotypes among the children of Mrs. Eryth (XAXa, carrier of the hemophilia allele) and Mr. Eryth (XAY, normal), you need to understand the inheritance patterns of sex-linked traits.
In humans, the X and Y chromosomes determine the sex of an individual. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). Hemophilia is a sex-linked trait that is carried on the X chromosome, meaning it is more commonly expressed in males.
Let's break down the genotypes and phenotypes of the potential offspring using a Punnett square:
XA Xa
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XA | XAXA XAXa
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XA | XAXA XAXa
In the Punnett square, the left column and top row represent the possible gametes from Mrs. Eryth, while the rows and columns represent the gametes from Mr. Eryth.
The possible genotypes in the Punnett square are:
- XAXA (normal female, not a carrier)
- XAXa (female carrier)
- XAY (normal male)
The corresponding phenotypes for each genotype are:
- XAXA: Normal female, not a carrier of hemophilia
- XAXa: Female carrier of hemophilia
- XAY: Normal male, not a carrier of hemophilia
Based on the Punnett square, all female offspring will be carriers of the hemophilia allele (XAXa), while all male offspring will be normal (XAY).
To create a Punnett square for a sex-linked trait like hemophilia, we need to consider the alleles on the X and Y chromosomes.
Since Mrs. Eryth is a carrier of the hemophilia allele (XAXa), she has one X chromosome with the hemophilia allele (Xa) and one X chromosome with the normal allele (XA).
Mr. Eryth is normal (XAY), which means he has one X chromosome with the normal allele (XA) and one Y chromosome.
Now, let's create a Punnett square to show the possible genotypes and phenotypes of their children:
| XA | Xa |
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XA | XAXA | XAXa |
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XA | XAXA | XAXa |
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Y | XAY | XaY |
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In the Punnett square, the top row represents the possible alleles from Mrs. Eryth (XA and Xa), while the first column represents the possible alleles from Mr. Eryth (XA and Y).
The outcomes in the Punnett square show that there is a 50% chance of their children being carriers (XAXa) and a 50% chance of them being normal (XAY).
Please note that since hemophilia is a sex-linked recessive trait, only boys can be affected by the disorder. Girls can only be carriers.