How Does Color Blindness Genetics Affect Offspring?

[glxvr6turbo]

1. A sex linked gene 'c' produces red-green color blindness in humans. A normal woman whose father is color-blind marries a color-blind man. What genotype(s) are/is possible for the mother of the color-blind man she has married?

a. What are the chances that the first child from this marriage will be a color-blind boy?

b. Of the daughters of these parents, what fraction are expected to be color-blind?

 

[ace123]

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[Blueshift5]

I would first like to clarify that the term "color blindness" in this context refers to the inability to distinguish between red and green colors, which is a result of a genetic mutation on the X chromosome. With that in mind, let's address the questions at hand.

The mother of the color-blind man in question could have two possible genotypes: XcX or XcXc. This means that she is either a carrier of the color blindness gene (Xc) or she is affected by color blindness herself.

a. The chances of the first child from this marriage being a color-blind boy would depend on the genotype of the mother. If she is a carrier (XcX), then there is a 50% chance that the first child will be a color-blind boy. However, if she is affected by color blindness (XcXc), then all of her sons will be color-blind.

b. Of the daughters of these parents, 50% are expected to be carriers (XcX) and 50% are expected to be unaffected (XX). This means that 50% of the daughters will have a chance of passing on the color blindness gene to their own children, but will not be affected by it themselves.

In summary, the mother of the color-blind man could have two possible genotypes and the chances of the first child being a color-blind boy depend on her genotype. Half of the daughters are expected to be carriers of the color blindness gene. These predictions are based on the assumption that the father is color-blind due to the sex-linked gene 'c'.