Download Sex Linked Inheritance

Name: ______________________________________Period: ________ X-­‐Linked Inheritance Sex linked inheritance -­‐ Includes traits found on the X and Y chromosome. Y Chromosome – X Chromosome – *Because human females are XX and males are XY certain X-­‐Linked recessive diseases occur more often in males then in females. Why? Red-­‐Green Colorblindness Genotype Phenotype Examples for Colorblindness: 1. If a heterozygous female marries a normal vision male. What are their genotypes and what are the genotypic and phenotypic ratios for their offspring. Parents: ____________x______________ Genotypic ratio: Phenotypic ratio: 2. If a homozygous female with normal vision marries a normal vision male. What are their genotypes and what are the genotypic and phenotypic ratios for their offspring Name: ______________________________________Period: ________ 3. Can two colorblind parents produce a normal son? Show punnett square & explain. 4. Can two normal parents produce a colorblind son? Colorblind daughter? Show punnett square and explain. 5. A normal woman whose father was colorblind marries a colorblind man. What proportion of their children will be colorblind? Show punnett square. 6. A normal man whose father was color-­‐blind marries normal woman who carries the color-­‐
blind allele. What proportion of their children will be color-­‐blind? Show punnett square. Name: ______________________________________Period: ________ In humans, hemophilia a disease where blood doesn’t clot. It is a sex-­‐linked trait. Females can be “carriers” of the disease but not have the disease. Males will either have the disease or not (they are never carriers). USE THE ABOVE INFORMATION FOR QUESTIONS 7-­‐8 7. Show the cross of a man who is normal and a woman who is a carrier. Key:____=___________________ ____=_____________________ Parents: ___________ x _____________ a) What is the percent chance that they will have a child with the disease? b) If a boy gets this disease, which parent gave him the hemophilia gene? 8. A woman who has hemophilia has a child with a normal man. Parents: ____________ x _____________ a) What is the percent chance that they will have a girl with hemophilia? b) What is the percent chance they will have a son with the disease? Name: ______________________________________Period: ________ Name: ______________________________________Period: ________