The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.

What is the probability that female I-3 is a heterozygous carrier of the allele for albinism? 

Key Concepts

Pedigree Analysis

Pedigree analysis is a diagrammatic method used to trace the inheritance patterns of traits through generations in a family. It helps identify whether a trait is dominant or recessive, and can indicate the genotypes of individuals based on their phenotypes and the phenotypes of their relatives. Understanding how to read and interpret pedigrees is crucial for determining the likelihood of genetic traits being passed on.

Autosomal Recessive Inheritance

Albinism is typically inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the recessive allele (one from each parent) to express the trait. Carriers, who have one dominant and one recessive allele, do not show the trait but can pass the recessive allele to their offspring. Recognizing this inheritance pattern is essential for calculating the probability of an individual being a carrier.

Probability in Genetics

Probability in genetics involves calculating the likelihood of certain genotypes or phenotypes occurring in offspring based on parental genotypes. This is often done using tools like Punnett squares or by applying the principles of Mendelian inheritance. In the context of the question, understanding how to assess the probability that female I-3 is a heterozygous carrier requires knowledge of the genotypes of her parents and the inheritance patterns of albinism.