Gregor Mendel

Who was he?

    Gregor Mendel was an Austrian monk, born in 1822. He discovered the basic principles of heredity through experiments in his garden with plants. One of his most famous revelations  was "The Law of Segregation" and "The Law of Independent Assortment". His observations have become the foundation of modern genetics and the study of heredity, hence giving him the name, "Father of Modern Genetics". 


    Mendel made the following hypotheses:

  1. In organisms, there is a pair of factors that controls the appearance of a given characteristic (we now call these characteristics genes).
  2. Organisms inherit these characteristics from their parents.
  3. Each is transmitted from generation to generation as a discrete, unchanging unit.
  4. When the gametes are formed, the factors separate and are distributed as units to each gamete. This statement is called The Law of Segregation.
  5. If an organism has two unlike factors (we call them alleles) for a characteristic, one may be expressed as a dominant or recessive.


In order to test his hypothesis, Mendel predicted the outcome of a breeding experiment that he had not yet carried out. He crossed heterozygous round peas (Rr) with wrinkled (homozygous, rr) ones. He predicted that in this case one-half of the seeds produced would be round (Rr) and one-half wrinkled (rr) . Mendel's famous punnet squares helped calculate the outcome of his peas. He predicted that the outcome of his peas would be 50:50 (50% for round peas and 50% for wrinkled peas).

- (Above) Punnet square, cross-over of heterozygous round peas and wrinkled peas.

Here is a better picture on how a Punnet square works.



    The outcome of his experiment (above) resulted to 106 round peas and 101wrinkled peas (close to the 50:50 ratio).  His prediction/hypothesis were indeed correct. He proved his hypothesis many times and also crossed plants that had 2 different traits (and so on).


    Mendel concluded that the phenotype of an organism depended on the genotypes of the parent on the organism, and that it is actually possible to calculate the phenotype of an offspring (with the use of punnet square).

How This Experiment Changed Our Knowledge of Genetics

    Mendel's experiments and work are known as Mendelian Inheritance. His work has become a basic knowledge of heredity and has a great impact on genetic diseases that we know today. For instance, we now know the reason why some people have blue color and some have brown eye color or why some families have a history of heart diseases and some don't.

Works Cited

Edward Bozin,
Jan 20, 2015, 11:41 PM