Description
A homologous chromosome is a pair of two chromosomes – one from the father, one from the mother. Heterozygous means that both alleles on a specific position on the homologous chromosomes differ from each other. In heterozygous individuals, one allele is dominant (displayed with a capital letter e.g. A) and one is recessive (displayed with a small letter e.g. a), so in this example, in the end we have Aa. The dominant allele is the one that will be expressed. For example, being heterozygous for a recessive trait like blue eyes means that it is unlikely to develop those. Being homozygous for this trait, on the other hand, means that you will have blue eyes.