Laws of Inheritance

• The basis of inheritance lies in two key principles

  1. The segregation of alleles of a single gene
  2. The independent assortment of different genes on different chromosomes
• The independent assortment of different genes on different chromosomes

  • The two alleles of one gene on one chromosome segregate into gametes independently of the two alleles of another gene on a different chromosome
• The segregation of alleles of a single gene

  • Individuals inherit two alleles of each gene, one from the mother and one from the father, and when that individual forms gametes, the two alleles separate equally into each gamete
• Segregation

  • Segregation reflects the separation of homologous chromosomes during anaphase I of meiosis (i.e., when the bivalent splits)
• Independent assortment

  • Independent assortment of genes on different chromosomes reflects the fact that nonhomologous chromosomes can orient in either of 2 ways at metaphase that are equally likely
• True breeding: the appearance of the offspring is identical to the parents over successive generations
• By the Principle of Segregation, when each true-breeding parent makes gametes, the seed color alleles on maternal homolog and paternal homolog will segregate (separate) during meiosis 1