Albinism in humans is inherited as a simple recessive trait. For the following families, determine the genotypes of the parents and offspring. (When two alternative genotypes are possible, list both.) A normal male and an albino female have six children, three normal and three albino.

Key Concepts

Recessive Traits

Recessive traits are characteristics that only manifest when an individual has two copies of the recessive allele. In the case of albinism, the trait is caused by a recessive allele, meaning that an individual must inherit this allele from both parents to express the condition. If an individual has one dominant allele, the dominant trait will be expressed instead.

Genotype vs. Phenotype

Genotype refers to the genetic makeup of an individual, specifically the alleles they carry, while phenotype is the observable expression of those genes. For example, a person with one dominant allele for normal pigmentation and one recessive allele for albinism would have a genotype of 'Aa' but a phenotype of normal pigmentation. Understanding the distinction between these terms is crucial for analyzing inheritance patterns.

Punnett Squares

Punnett squares are a tool used in genetics to predict the possible genotypes of offspring from a cross between two parents. By mapping out the alleles contributed by each parent, one can visualize the probability of different genotypes and phenotypes in the offspring. This method is particularly useful for simple Mendelian traits, such as albinism, to determine the expected ratios of normal and albino children.