Gregor Mendel conducted breeding experiments with pea plants in the 1850s and discovered the laws of inheritance. Through his accurate record keeping and large sample sizes, he found that traits are passed from parents to offspring through discrete units called genes. Mendel also discovered that for each trait, there are two versions of each gene, called alleles, with one allele being dominant and the other recessive. Through his experiments, he developed the laws of segregation and independent assortment, which describe how alleles separate and assort during the formation of gametes. Mendel's discoveries formed the foundation of classical genetics.

1. Mendel and the Gene Idea