Pre mendalian ideas about heredity

Mendal (1866) proposed that inheritance is controlled by paired germinal units or factors , now called genes. Genes are present in all cells of the body and are transferred to the next generation through gametes .Factors or genes are thus physical basis of Heredity.

1. Course Teacher Dr. M. Kanimoli Mathivathana Assistant Professor Department of Plant Breeding & Genetics PRESENTED BY M. THARANI ID No.: 2017021080 COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University,Coimbatore-3) ((Accredited by Indian Council of Agricultural Research, New Delhi) Kullapuram (Po), Via Vaigai Dam, Theni - 625 562.

2. PRE MENDALIAN IDEAS ABOUT HEREDITY

3. Mendal (1866) proposed that inheritance is controlled by paired germinal units or factors , now called genes. G enes are present in all cells of the body and are transferred to the next generation through gametes . F actors or genes are thus physical basis of Heredity. MENDAL THEORY

4. Everyone had a question how a offspring produced from a parent which is similar to his / her parent or their grand parents . Before the correct definition given by Mendal how the people or scientist have a idea about heredity [ ie before 1866 ] Thus the concept or ideas or theories arise before the Mendal discovery are said to be Pre – Mendalian Theories . HOW PEOPLE THINK EARLIER ???

5. The V apour Theory The Fluid Theory The Theory of Spontaneous Generation The Magnetic Power Theory The Preformation Theory The Theory of Epigenesis PRE MENDALIAN THEORY :

6. The Particulate Theory The Theory of Acquired characters The Theory of Pangenes The Germplasm Theory Evolution Theory of Inheritance by natural selection Mutation Theory of Inheritance

7. 1. THE VAPOUR THEORY Greek Philosopher Pythagorus (600 BC ) M oist vapour From body of male Development of embryo In uterus of female

8. 2. THE FLUID THEORY Proposed by the Greek Philosopher Empeddes

9. 3. THE THEORY OF SPONTANEOUS GENERATION The G reek Biologist Aristotle

10. 4. MAGNETIC POWER THEORY WILLIAM HARVEY ( 1578 – 1657 ) Experiment made on deer

11. 5. THE PREFORMATION THEORY SWAMMERDAN & BONNET (1720-1793 )

12. 6. THE THEORY OF EPIGENESIS WOLFF ( 1738 – 1794 ) This concept was universally accepted

13. 7. THE PARTICULATE THEORY MAUPERTIUS ( 1698 – 1758 )

14. 8.THE THEORY OF ACQUIRED CHARACTERS Proposed by JEAN BAPTISTE DE LAMARCK ( 1744 – 1829 ) This theory was disproved by Weismann

15. 9. THE THEORY OF PANGENES CHARLES DARWIN (1809 – 1882 ) Very small , exact but individual copies of each body organ called gemmules

16. 10.THE GERMPLASM THEORY ( 1887 ) AUGUST WEISMANN ( 1834 – 1917 ) Reduction in chromosome no during the formation of egg and sperm Restore when the egg and sperm fused

17. 11. EVOLUTIONARY THEORY OF INHERITANCE BY NATURAL SELECTION Proposed by CHARLES DARWIN BATESON – disagree - he believed evolution due to large discontinous variations Evolution is due to natural selection of small heredity variations according among individuals of any species .

18. 12. MUTATION THEORY OF INHERITANCE ( 1901 ) DE VERIES ( 1848 – 1935 ) Observed in some plants Oenothera lamarckiana Introduced term mutation for these large discontinous variation in the genotype

19. REFERENCES Krishnan V . Senthil N . Kalaiselvi Senthil .2018 . Third edition , Thannanmbikkai Publications , Coimbatore . Pp 1 – 8 Karvita .b . Ahluwalia , 1996 . Genetics , second edition , New age international Publishers , New Delhi . Pp 1 – 10 Roberts .H.F. 1929. Plant Hybridisation before Mendal . Princeton University .Press . n.J Whitehouse , H.L.K . 1973 . Mechanism of Heredity . Third edition . S.t. Martin’s Press , New York . Pp 8 – 9

20. Mc Kusick .v. 1969 . Human Genetics . Second edition . Prentice hall . N.J . Jaipur . Dunn .L.C . 1965 . A Short History of Genetics – MC Graw – hill , NewYork . Carlson.E.A.1966. The Gene: A Critical History . Sauders , Philadelphia . Phudan S ingh . 2005 . Genetics . First edition . Kalyani Publishers , New Delhi . Pp 11 – 20 . Acquaah george . 2006. Principles of Plant Genetics and Breeding. Black well Publishers . Pp 4 -6 .