An overview of Gregor Johann Mendel and his experiments

• Gregor Johann Mendel is known as the Father of Genetics. Actually he was a meteorologist, mathematician, biologist and a monk.

• Mendel observed variations in the field of pea. By seeing these variations, he decided to know the real facts of these variations.

• Variation is a degree or parameter by which  offspring look different from their parents. For example: Sahiwal cow breed in Punjab  was developed on the basis of variation through the Artificial selection.

• Mendel discovered the basic principles of heredity through experiments . His experiments showed the inheritance of certain traits in pea plants. He founded modern genetics and led to the study of heredity.

• He conducted his experiments on the Garden Pea plant or Pisum sativum for seven years from 1856 to 1863.

• He selected fourteen true breeding plants of Pea and considered seven contrasting characters in pea plants. These seven characters are as follows- 

• Seed  Shape -round or wrinkled
• Seed  color -  green or yellow
• Pod shape - constricted or inflated
• Pod color -green or yellow
• Flower color - Violet or white
• Stem hight - tall or dwarf 
• Position of flowers - axial or terminal.

Facts about Mendel's Experiments 

• Mendel took Fourteen true breeding plants. Mendel considered seven contrasting characters during his experiments.

• Mendel considered only Single characters at once during his experiments. He was first to use Mathematics in Biology. Mendels was lucky because there was no linkage phenomenon in pea plants. 

👌👌Remember - Mendel coined the term dominant and recessive.

Selection of Pea Plant for Experiments 

• Pea plant is an annual plant with a short life span so several generations can be studied in a short period. It is perfect bisexual flower containing both male and female reproductive flowers.

• It easily self pollinated and also  cross pollinated by doing the emasculation. It produces a large number of seeds in one generation. Pea plants are easily handled and maintained.

Mendel's observation and

inference

• The characters that are controlled in pea plants are coded by some factors.

• These factors are passed from one generation to another generation without any changes. These factors are found in pairs.

• The hybrid or offspring show combined characters of parental form.

• The traits also  appeared in another generation without any change.

• The two contrasting traits do not show any blending or mixing in any generation.

• Mendel was first to use Mathematical and statistical logic in Biology.

Terms used in Mendel's experiments and observation

• Factors or gene which code for a pair of contrast character called allele. Allele is slightly different from the gene. Gene is unit of inheritance. Allele is expressed by a pair of alphabetically system

• Mendel conducted a cross between a single trait called monohybrid cross and also between two traits called dihybrid cross.

• Mendel used the term allele for coding the traits that are similar in homozygous like AA  or dissimilar in heterozygous like Aa.

• He analysed two types of ratio during his result. First, the ratio of external appearance in pea plants is called phenotypic ratio and the second ratio of allelic forms is called genotypic ratio.

• A British scientist Reginald C Punnett developed a square to calculate the genotypic and phenotypic ratio called Punnett Square or CheckerBoard.

• Mendel conducted their Experiments on Garden pea up to 1865 but work of Mendel was unknown for Biologist till 1900. 

• Because in those days,  communication was not easy therefore his work could not be widely publicised. 

• Secondly, his concept of genes or factors as stable and discrete units that controlled the expression of traits and concept of the pair of alleles which did not 'blend' with each other, was not accepted by Biologist of  those days.

• Thirdly, Mendel's approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time. 

• In addition to this, Mendel's could not provide any physical proof for the existence of factor.