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, all normal.

Verified step by step guidance

1. Identify the inheritance pattern: Albinism is a recessive trait, so the genotype for albinism is homozygous recessive (aa), and normal pigmentation can be either homozygous dominant (AA) or heterozygous (Aa).
2. Determine the genotype of the albino female parent: Since she shows the recessive phenotype, her genotype must be aa.
3. Analyze the normal male parent's genotype: Because all six children are normal but the mother is aa, the father must carry at least one dominant allele (A). Since some children could be carriers, the father could be either AA or Aa.
4. Predict the genotypes of the offspring: Each child receives one allele from each parent. Since the mother is aa, all children receive an a allele from her. The father's contribution determines the child's genotype: if the father is AA, all children will be Aa (normal carriers); if the father is Aa, children could be either Aa (normal carriers) or aa (albino), but since all children are normal, the father is more likely AA or the Aa children did not inherit the recessive allele from the father.
5. Summarize possible genotypes: Parents - Male: AA or Aa, Female: aa; Offspring - all normal, so genotypes are either all Aa (if father is AA) or a mix of Aa and possibly aa (if father is Aa), but since no albino children are observed, the father is most likely AA.

Key Concepts

Recessive Inheritance

Recessive inheritance means a trait is expressed only when an individual has two copies of the recessive allele. In albinism, the condition appears only if the genotype is homozygous recessive (aa). Carriers with one dominant and one recessive allele (Aa) show a normal phenotype but can pass the recessive allele to offspring.

Genotype and Phenotype Relationship

Genotype refers to the genetic makeup (allele combination) of an organism, while phenotype is the observable trait. For albinism, individuals with AA or Aa genotypes have normal pigmentation, whereas aa individuals are albino. Understanding this helps predict offspring traits based on parental genotypes.

Punnett Square and Probability in Genetics

A Punnett square is a tool used to predict the possible genotypes of offspring from parental alleles. It helps calculate the probability of inheriting specific traits, such as albinism, by combining parental alleles. This method is essential for determining possible genotypes when given phenotypes.