AP BIOLOGY

Detailed explanation-1: -In X-linked recessive inheritance, a daughter inherits a single mutated gene on the X chromosome from one of her parents. The X chromosome she inherits from the other parent will usually cancel the effect of the mutation, and she most likely will not have the genetic condition.

Detailed explanation-2: -Females can get an X-linked recessive disorder, but this is very rare. An abnormal gene on the X chromosome from each parent would be required, since a female has two X chromosomes.

Detailed explanation-3: -1 in 4, (25%) chance that a daughter will inherit from their father the working copy of the X-linked gene and the X-linked recessive nonworking gene copy with a variant from the mother. This person will be a genetic carrier of the condition like the mother and will usually be unaffected.

Detailed explanation-4: -A female with Turner syndrome will only have one X and will therefore express “X-linked recessive” conditions just as a male would. A female with an ‘XXX’ genotype may have a different X-inactivation pattern. A male with an ‘XXY’ genotype may express milder phenotype due to his X-inactivation pattern.

Detailed explanation-5: -Because females have two X chromosomes, carriers have a second, normal (or ‘wild-type’) copy of the gene. This means that female carriers are usually not affected by X-linked recessive conditions, or affected only mildly. They may pass either X chromosome to their children.