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Genetics
Genetics is the branch of biology which deals with the study of heredity and variations. The term genetics was first used by W.Bateson (1905).

Follow up:

Heredity: is the study of transmission of characters from parents to the offspring.
Mendel used the term Factor for the hereditary unit which is now called as gene. (Johannson coined the term gene, phenotype and genotype).
R.de.Graff (1641-1673) suggested that both the parents should contribute to heredity.
Carl Nageli (1884) was the first to propose a theory regarding heredity.
Variation: the differences that exist among the individuals of the same species are called variation.

There are two types of variations.
1. Variations caused due to the genetic differences is called genetic or hereditary variations
2. Variations caused due to the environmental factors and which is not permanent is called environmental variation.

Gregor Johann Mendel and his work:
He is an Austrian monk born in1822 to a poor peasant parents in Heinzendorf village of Sicilian region (now part of Czechoslovakia).

At the age of 21, he joined Austrian monastery of st.Thomas in Brunn he received his basic education here. Later Mendel was sent to university of Vienna for studying physics and botany in 1851.

• He returned in 1854 and was made besides a monk, substitute science teacher for physics and natural science.

• In 1856 his attention was drawn towards garden pea plant (Pisum sativum)       grown in monastery.   (Chromosome number in pisum sativum is 14 (2n).

• In 1856 he started series of hybridization experiment to study plant heredity in the garden pea plant

• From 1857 -1859 Mendel collected 34 varieties of pea plants and allowed them to breed for obtaining pure forms. Among them he selected only seven varieties for his experiment.

• From 1859-1865 he conducted hybridization experiments in different varieties.

• He published his theories in two sittings. One in 1865 in the natural History society of Brunn.

• The same were published in 1866 in the 4th volume of proceedings of Natural History Society of Brunn under the title ‘Experiments on plant hybridization’.

• Mendel died in 1884 before his work being accepted.

• After 16years of his death that is in 1900 his work re-emerged due to the independent work of the three European scientists namely:

Hugo De Vries-Holland
Erich Von tschermark-Austria
Carl Correns-Germany and published Mendel’s laws and principles and finally Mendel is accepted as ‘Father of Genetics’.
Archibald Garrod is considered as ‘Father of human genetics’

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