A colorblind male marries a normal female. What are the offspring genotypes and phenotypes?

Understand the Problem

The question is asking about the genetic outcomes for the offspring of a colorblind male and a normal vision female. Specifically, it seeks to determine both the genotypes and phenotypes of their children based on the inheritance patterns of colorblindness, which is a sex-linked trait.

Answer

50% normal vision carrier females (X₁Xᶜ) and 50% normal vision males (X₁Y).

Steps to Solve

Identify the genotypes
Colorblindness is a sex-linked recessive trait carried on the X chromosome. The notation we'll use is:

Normal vision female: X₁X₁ (where X₁ represents the normal vision allele)
Colorblind male: XᶜY (where Xᶜ represents the colorblind allele)

Set up the Punnett square
A Punnett square can help us visualize the potential genotypes of their offspring. We'll place the mother's alleles on one side and the father's on the other.

Mother (X₁X₁)
Father (XᶜY)

The Punnett square will look like this:

       X₁   X₁  
     ----------------  
Xᶜ | X₁Xᶜ | X₁Xᶜ |  
Y   | X₁Y   | X₁Y   |

Fill in the Punnett square
Now we'll fill in the genotypes:

X₁Xᶜ (carrier female, not colorblind)
X₁Y (normal vision male)

Determine phenotypes
From the completed Punnett square, we can derive the phenotypes:

X₁Xᶜ: normal vision (carrier, female)
X₁Y: normal vision (male)

Calculate the ratios
Now, we can summarize the ratios from the Punnett square:

2 normal vision females (X₁Xᶜ)
2 normal vision males (X₁Y)

The offspring's expected ratio is:

50% normal vision females
50% normal vision males

The genotypes of the offspring are:

50% X₁Xᶜ (normal vision, carrier female)
50% X₁Y (normal vision male)

More Information

In sex-linked inheritance, it is important to remember that males inherit their X chromosome from their mother and the Y chromosome from their father. This is why a mother plays a crucial role in passing colorblindness to male offspring.

Tips

Not realizing that males get their X chromosome from their mother, leading to confusion about which parent contributes the trait.
Forgetting to consider carriers in the genotype, which can lead to incorrect phenotype ratios.

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