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Presentation on pre mendelian and post mendelian theory

Presentation on Pre-mendelian and Post Mendelian Theory

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Presentation on pre mendelian and post mendelian theory

  1. 1. Prepared by- Uttam Kumar Naik B.Sc(Ag) 11c/15
  2. 2.  Various views are prevelling about the process of heredity before the rediscovery of Mendel laws of inheritance.  Some of these concept are given below-
  3. 3.  Given by Pythagorous.  The body of male produce moist vapour during coitus which form the body part of embryo.
  4. 4.  Given by Empedocles.  Each body part produce a fluid .The fluid of different body part of two parent mix up and is used in formation of embryo.
  5. 5.  Given by Aristole. The male produce highly purified reproductive blood containing the nutrient. Female produce reproductive blood that is impure. The two reproductive blood coagulate in the body part of the female and form embryo. Due to purity of reproductive blood the contribution of character by male is mark.
  6. 6.  Given by Swammerdan and Bonnet. This theory states that a miniature human, called homunculus,is already present in the egg and sperm which grow into human being after formation of zygote
  7. 7.  Given by german biologist Wolff.  The egg and sperm are undifferentiated cell. The differentation into various organ takes place only after fertilization in the zygote.Reulting in the development of adult tissue.  It is universally accepted.
  8. 8.  Proposed by French Biologist Lamarck.  A new character acquired by an individual cell pass into progeny.  It means if a man develop a strong muscle by exercise all his children would have strong muscle.  It was totally rejected by Weismann.
  9. 9.  Given by Weismann.  He experiment on rat by cutting their tails and observed the progeny for 22 generation. In every generation rat progeny continued to have tails inspite of the fact that the parent were tailless.  In this way it discard theory of acquired character.
  10. 10.  The basic principle of hereditary initially discovered by Mendel in 1866.  Rediscovered by De Vries, Correns, Tschermak in 1900.  These new concept were different from finding of Mendel.  These concept are often refered as “Mendelian Deviation”.
  11. 11.  Incomplete dominance.  Co-dominance  Multiple alleles  Linkage  Lethal gene  Gene interraction  Pleiotropic gene effect  Polygenes  Environmental effect  Cytoplasmic effect