Final answer:
The trait in the pedigree is a genetic characteristic passed through generations, with individuals 1, 2 and 3 having genotypes aa, AA, and AA, respectively. Pedigree analysis helps determine inheritance patterns, including if a trait is autosomal or sex-linked, and dominant or recessive.
Step-by-step explanation:
The trait in the pedigree is a genetic characteristic that has been passed through a family's generations. A pedigree analysis helps to understand the inheritance patterns of this trait. When analyzing a pedigree, one can determine if the trait is autosomal or sex-linked, and whether it is dominant or recessive. The genotypes of the individuals labeled 1, 2 and 3 in the given pedigree are aa, AA, and AA respectively. This indicates that individual 1 is homozygous recessive for the trait, while individuals 2 and 3 are homozygous dominant.
In the context of a pedigree showing the inheritance of a recessive disorder, an individual with genotype 'aa' would have the disorder and be represented in blue, while 'AA' or 'Aa' would be unaffected and indicated in yellow. This assists in predicting the probability of offspring inheriting a particular genetic disorder or trait. For instance, a single-gene autosomal dominant trait such as free-hanging earlobes can be represented in a pedigree where the dominant allele (A) for the trait is expressed when present.
It's also important to highlight that males will always express a recessive X-linked allele because they have only one X chromosome. In order for a recessive X-linked allele to be expressed in females, they must have two copies of the allele, one on each of their two X chromosomes. An example of a recessive X-linked trait is hemophilia.