AP BIOLOGY

Detailed explanation-1: -X-linked recessive pedigree. Marriage between a male with an X-linked recessive trait (aY) and an unaffected woman (AA) produces children with one of two genotypes. All of the sons will are AY, with the Y chromosome from the father and an A allele from the mother.

Detailed explanation-2: -Examples of X-linked recessive conditions include red-green color blindness and hemophilia A: Red-green color blindness. Red-green color blindness simply means that a person cannot distinguish shades of red and green (usually blue-green).

Detailed explanation-3: -Females will have two X-linked alleles (because females are XX), whereas males will only have one X-linked allele (because males are XY).

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.