Nondisjunction and its implications ppt

non-disjunction and its implications

1. NON-DISJUCTION AND ITS IMPLICATIONS BY-POOJA PRAVIN KAMBLE M.S C part-one

2. PSZO103: GENETICS,EVOLUTION AND DEVELOPMENTAL BIOLOGY UNIT I: GENETICS-CHROMOSOME THEROY OF INHERITANCE AND MENDELISM-1 1.1:MITOSIS AND MEIOSIS 1.1.3-NON-DISJUCTION AND ITS IMPLICATOON

3. CONTENTS INTRODUCTION DEFINATION DISCOVERY OF NON-DISJUCTION TYPES OF NON-DISJUCTION DISORDERS DUE TO NON-DISJUCTION CONCLUSION REFRENCES

4. BASICS OF NON-DISJUCTION WHAT IS NON-DISJUCTION? HOW DO INDIVIDUALS GET NON-DISJUCTION? WHAT HAPPENS DURING NON-DISJUCTION? WHY NON-DISJUCTION HAPPEN? WHAT IS THE CAUSE OF NON-DISJUCTION? WHEN DOES NON-DISJUCTION OCCUR? AT WHICH PHASE NON-DISJUCTION OCCURS?

5. INTRODUCTION Proper disjuction separates the two homologus chromosomes during cell division. When there is a faliure of two homologus chromosomes or sister chromatids to separate during cell division it is called as NON-DISJUCTION

6. DEFINATION Non- disjuction is the failure of chromosome pairs to separate during meiosis stage 1 or meiosis stage 2 specifically in the anaphase.

7. DISCOVERY OF NON-DISJUCTION Non- disjuction was discovered in crosses between white eyed female drosophilla and red eyed male drosophilla All F1 generations should have white eyed males and red eyed females In 1913 calvin bridges found that there are rare exceptions to this results,he found few white eyed daughters and red-eyed sons among F1 generations.

8. TYPES OF NON-DISJUCTION   1)MEIOTIC NON-DISJUCTION 2)MITOTIC NON-DISJUCTION

9. TYPES OF NON-DISJUCTION

10. MEIOTIC NON-DISJUCTION Non- disjuction may occur during either the I or II meiotic division. If non- disjuction occurs during 1 st meiotic division then all the sperm derived from that primary spermatocyte will be abnormal. In humans for example these sperm will end up with a total of 22 or 24 chromosomes rather than the ususal 23.

11. If non- disjuction occurs in a secondary spermatocyte undergoing meiosis II,then only two of the four sperm will be abnormal.

12. MITOTIC NON-DISJUCTION Mitotic non- disjuction gives mosaic cells with different number of chromosome numbers. This is a caused by a breaking of the spindle fiber during metaphase or anaphase. For example, if spindle fibers do not form for one of the chromosomes, then during anaphase it will not separate into two chromatids and one cell will have an extra chromatid and the other will be lacking one. This causes a trisomic and a monosomic daughter cell to be formed, which produces a mosaic of cell types in the individual.

13. CHROMOSOMAL NON-DISJUCTION AUTOSOMES 1)PATAU SYNDROME 2)EDWARD SYNDROME 3)DOWNS SYNDROME SEX CHROMOSOMES 1)TURNER SYNDROME 2)KLINEFELTER SYNDROME 3)SUPER MALE SYNDROME 4)SUPER FEMALE SYNDROME

14. PATAU SYNDROME

15. EDWARD SYNDROME

16. DOWN SYNDROME

17. TURNER SYNDROME

18. KLINFELTER SYNDROME

19. SUPER MALE SYNDROME

20. SUPER FEMALE SYNDROME

21. PHILADELPHIA SYNDROME

22. CRI-DU CHAT SYNDROME

23. D-G TRANSLOCATION SYNDROME

24. CONCLUSION To identify new mutations that are defective at some step in chromosome segregation. Use of nondisjunction to prove the chromosome theory of heredity ( Bridges 1916 ). The current study provides guidance for researchers designing genetic experiments on nondisjunction and improves several methods for the analysis of genetic data. Study of non- disjuction provides a use full model for studying the association of increasing maternal age and recombination.

25. REFRENCE Principles of genetics-Robert H.Tamarin Concepts of genetics- williams S.Klunge i -genetics- russell

26. THANK YOU