Final answer:
In a pedigree for autosomal recessive inheritance, an affected individual (II-1) has the homozygous recessive genotype 'aa', whereas unaffected individuals have a genotype of either 'AA' or 'Aa'.
Step-by-step explanation:
In a pedigree showing autosomal recessive inheritance, the genotype of an affected individual (II-1) must be homozygous recessive, which is represented as 'aa'. This indicates that both alleles for the gene in question are the recessive variant. Whether an individual will exhibit the phenotype for an autosomal recessive disorder depends on these alleles; only individuals with two copies of the recessive allele (aa) will show symptoms of the disorder.
Unaffected individuals may either be homozygous dominant (AA) or heterozygous (Aa). However, they will not show symptoms of the disorder because they have at least one dominant allele. The precise genotypes of individuals labeled 1, 2, and 3 in the pedigree would be 1- aa, 2- AA, 3- AA respectively. These genotypes reflect the inheritance pattern seen in conditions such as cystic fibrosis, where carriers of the trait may not show any symptoms but can still pass the recessive allele to their offspring.