Inheritance is the acquiring of genetic characteristics or traits from parents by their offspring. In humans, both parents equally contribute to the inheritance of traits. In 1860, Gregor Mendel studied the rules of inheritance of traits. He conducted an experiment on pea plants for the same. He cultivated pea plants and observed their pattern of inheritance from one generation to the next generation. This observation resulted in the discovery of three laws of inheritance, famously known as Mendel’s laws of Inheritance. Let us have a brief discussion on the contribution of Mendel in establishing the law of inheritance of traits.
Mendel’s Contribution to the 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 inheritance. Another experiment was based on two characters (seed shape and colour), thus called dihybrid inheritance.
Here, Mendel crossed one tall and short pea plant and a tall plant was formed. He called this as 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 which 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 Law of Segregation and Law of Dominance.
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.
Check Dihybrid Cross and Inheritance of Two Genes to know more about this type of inheritance.
Later, based on the conclusions and observation of Mendel relation between traits and inheritance, factors (genes) responsible for heredity were discovered.
To know more about Mendel’s experiments and laws of inheritance, visit the links given above.
|Genetics: Principles of Heredity||Mendelian Genetics|
|Mendel’s Laws of Inheritance||Mendel’s Law of Inheritance – Experiments|
|Incomplete Dominance & Mendel’s Experiment||Mendelian Disorders in Humans|