In heterozygous individuals, the only allele that is expressed is the dominant. The presence of an allele does not promise that the trait will be expressed in the individual that possesses it. If the two alleles are different, the individual is called heterozygous. If the two alleles are identical, the individual is called homozygous for the trait. The two factors may or may not contain the same information. One allele is given by the female parent and the other is given by the male parent. Thus, he formed the 'first rule', the Law of Segregation, which states individuals possess two alleles and a parent passes only one allele to his/her offspring. Mendel stated that each individual has two alleles for each trait, one from each parent. In the F2 generation, approximately three-quarters of the plants had violet flowers, and one-quarter had white flowers. The resulting hybrids in the F1 generation all had violet flowers. Mendel's Pea Plants: In one of his experiments on inheritance patterns, Mendel crossed plants that were true-breeding for violet flower color with plants true-breeding for white flower color (the P generation). The capital A represents the dominant factor while the lowercase a represents the recessive. After Mendel self-fertilized the F1 generation and obtained an F2 generation with a 3:1 ratio, he correctly theorized that genes can be paired in three different ways for each trait: AA, aa, and Aa. The dominant gene, such as the purple flower in Mendel's plants, will hide the recessive gene, the white flower. Each member of the pair becomes part of the separate sex cell. Mendel said that factors, later called genes, normally occur in pairs in ordinary body cells, yet segregate during the formation of sex cells. He then conceived the idea of heredity units, which he called 'factors', one of which is a recessive characteristic and the other dominant.

Rather than being a mix of the two colors, the offspring was purple flowered. Mendel discovered that by crossing true-breeding white flower and true-breeding purple flower plants, the result was a hybrid offspring. He described these laws in a two part paper, 'Experiments on Plant Hybridization', which was published in 1866. From these experiments, he deduced two generalizations that later became known as Mendel's Laws of Heredity or Mendelian inheritance. Between 18, he cultivated and tested some 28,000 pea plants. The laws of inheritance were derived by Gregor Mendel, a 19th century monk conducting hybridization experiments in garden peas ( Pisum sativum). The tenets were initially derived from the work of Gregor Mendel published in 18, which was 're-discovered' in 1900 they were initially very controversial, but they soon became the core of classical genetics. Mendelian inheritance (or Mendelian genetics or Mendelism) is a set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their children it underlies much of genetics.

allele: one of a number of alternative forms of the same gene occupying a given position on a chromosome.

heterozygous: of an organism which has two different alleles of a given gene.

homozygous: of an organism in which both copies of a given gene have the same allele.

Mendel cross-bred dihybrids and found that traits were inherited independently of each other.

If the two alleles are identical, the individual is called homozygous for the trait if the two alleles are different, the individual is called heterozygous.Mendel's Law of Independent Assortment states the inheritance of one pair of factors ( genes ) is independent of the inheritance of the other pair.Mendel's Law of Segregation states individuals possess two alleles and a parent passes only one allele to his/her offspring.By crossing purple and white pea plants, Mendel found the offspring were purple rather than mixed, indicating one color was dominant over the other.

Principle of independent assortment