Once in a while we all have gone through the term ‘genes’. We know that genes are the basic physical and functional unit of heredity which determine the nature of protein formed and those expressing the characteristics passed on from one generation to another generation. Least do we know about who experimented and discovered the same. Gregor Johann Mendel, also known as the father of modern genetics, discovered the ‘factors’ that were responsible for the transfer of characters from parents to off springs, which were later known to be the genes.
WHO WAS GREGOR MENDEL?
Gregor Johann Mendel was an Austrian Monk, a meteorologist, mathematician, biologist born in 1822 near Brunn in Austria. Born to a family with limited means in German-speaking Silesia, Mendel was raised in a rural setting. His academic abilities were recognized by the local priest who urged his parents to send him away to school at the age of 11. His Gymnasium studies(grammar school) completed in 1840, Mendel entered a two-year program in philosophy at the Philosophical Institute of the University of Olemouc, Czech Republic, where he excelled in physics and mathematics completing his studies in 1843. His initial years away from home were hard, because his family could not sufficiently support him. He tutored other students to make ends meet and twice he suffered serious depression and had to return home to recover from the same. As his father’s only son, Mendel was expected to take over the small family farm, but he preferred a different solution to his predicament, choosing to enter monastery(local community or residence of a religious order) where he was given the name Gregor.
However, in 1850 Mendel failed an exam- introduced through new legislation for teacher certification and was sent to the University of Vienna for 2 years. There he devoted his time in physics and mathematics and also studied botany. In 1854, Abbot Cyril Napp permitted Mendel to plan a major experimental program in hybridization at Monastery. The aim of this program was to trace the transmission of hereditary characters in successive generations of hybrid progeny. Mendel chose to conduct his studies with the edible pea(Pisum sativum).
From 1854 to 1856 he tested 34 varieties for constancy of their traits. In order to trace the transmission of characters, he chose seven traits that were expressed in a distinctive manner, such as:-
- plant height(short or tall)
- seed color(green or yellow)
- seed shape(smooth or wrinkled)
- pod color(green or yellow)
- pod shape(inflated or pinched)
- flower color(purple/grey or white)
- flower position(axial or terminal)
He crossed the varieties that differed in just one trait- tall plant with short plant(monohybrid cross). The first generation of hybrids(F1) displayed the character of one variety but not that of the other. In Mendel’s term, one character was dominant and the other was recessive. In the second generation(F2), however, the recessive character reappeared, and the proportion of off springs bearing the dominant and recessive trait was in the ratio 3:1.
WHY DID MENDEL CHOOSE PEA PLANT FOR HIS EXPERIMENTS?
- Flower structure of pea plant ensured self-pollination and also had a well defined male and female reproductive structures.
- pea plant is a single season crop.
- they can be grown easily.
- emasculation and pollination of flowers is quite easy
- these plants reproduce sexually.
- they have easily distinguishable pair of characters.