Inheritance can be defined as the process of how a child receives genetic information from the parent. The whole process of heredity is dependent upon inheritance and it is the reason that the offsprings are similar to the parents. This simply means that due to inheritance, the members of the same family possess similar characteristics. This understanding of inheritance was made possible by a scientist named Gregor Mendel, who formulated certain laws to understand inheritance known as Mendel’s laws of inheritance.
Mendel’s Inheritance Law
Mendel is known as the father of genetics. Mendel’s laws are Law of Dominance, Law of Segregation, and Law of Independent Assortment. These laws came into existence from experiments on pea plants with a variety of traits.
In the first experiment, only a single character (plant height) was considered and was known as monohybrid. Another experiment was based on two characters (seed shape and color), thus called dihybrid inheritance.
- Monohybrid Inheritance: Here, Mendel crossed one tall and short pea plant, and a tall plant was formed. He called this first-generation (F1) and offspring were called F1 progeny. Again, he obtained the second generation by crossing F1 progeny with parent plants. This resulted in both tall and short plants in the ratio of 3:1. Mendel observed that traits that were absent in F1 generation had reappeared in the F2 generation. He called such suppressed traits as recessive traits and expressed traits as dominant traits. These observations led to the formulation of the Law of Segregation and the Law of Dominance.
- Dihybrid Inheritance: Mendel took two contradicting traits together for crossing i.e. color and shape of seeds. He chose a round yellow seed and a wrinkled green seed and crossed them. He obtained only round yellow seeds in the F1 generation. Then, F1 progeny was self-pollinated, which gave four different combinations of seeds i.e. round-yellow, wrinkled-yellow, round green, and wrinkled green seeds in the F2 generation. Thus, he concluded that characters are distributed independently and inherited independently. Based on this observation he developed his third law – Law of Independent Assortment.