- #1
ethicaldesign
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Homework Statement
Color-blindness in humans is a sex-linked recessive trait. A color-blind man marries a woman who has normal vision and they have four children, one girl and three boys. The man has a sister who sees normally and a brother who is also color-blind, but their father (the paternal grandfather of the four children) sees normally. The woman also has a sister and a brother, both of which see normally even though their father (the four children's maternal grandfather) was color-blind.
A. Draw a pedigree for this situation showing all four grandparents, the two parents and their siblings, and the four children. Include appropriate symbols for sexes and phenotype along with appropriate genotype notations. if the genotype is not known, then put only the possible genotypes based on the information given.
B. What is the probability that two out of the three boys will be color-blind>?
C. What is the probability that all four children will be color-blind?
D. The family just had a set of identical twin boys (hooray!) What are the chances of both twins being color-blind?
Homework Equations
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The Attempt at a Solution
I've tried considerably to draw the pedigree, but I cannot get it to accurately correspond with the genetics. Without this, I cannot proceed to the other questions. Will someone please help me?