MEIOSIS

1. MEIOSIS Object: to study the meiosis through its subsequent developmental stages and discuss its Genetics Significant..

2. Meiosis • Meiosis in males is called spermatogenesis and produces sperms. • Meiosis in females is called oogenesis and produces ova. • Two divisions (meiosis I and meiosis II).

3. MITOSIS Somatic cells 2n 1 cell division: 2 daughter cells 2n 2n MEIOSIS Cells in sexual cycle 2 cell divisions: 4 cells product of meiosis n n n 2n n n n n=chromosome number

4. definitions • Homologous chromosomes:the members of a chromosome pair that is identical in the arrangement of genes

5. Homologous Chromosomes eye color locus eye color locus hair color locus hair color locus Paternal Maternal

6. definitions • Synapsis: (التشابك) the intimate association ترابط وثيق)) of homologous chromosomes… Homologous chromosomes

7. definitions • Crossing-over: (العبور) a term describing the process of reciprocal chromosomal interchange by which recombinants arise

8. Crossing over Pairing of homologous chromosomes Chiasma formation Chromosomes Breakage and joining Recombinant chromosomes

9. MEIOSIS I • Prophase I • The longest phase. This phase can be divided into 5 stages; a) Leptotene b) Zygotene c) Pachytene d) Diplotene e) Diakinesis

10. 1. Leptotene Prophase I 5.Diakinesis 4.Diplotene 2.Zygotene 3.Pachytene

11. Prophase I Metaphase I Anaphase I Telophase I Prophase II

12. Meiosis 2nd division: like mitosis with haploid set

13. 4 Haploid cells Gametes

15. Mitosis vs Meiosis

16. Slides for Meiosis I & II: Prophase I

17. Metaphase I:

18. Anaphase I:

19. Telophase I:

20. Prophase II:

21. Metaphase II:

22. Anaphase II:

23. Telophase II:

24. Final result Mitosis : two genetically identical diploid cells from one diploid parent cell Meiosis : Four genetically different haploid cells from one diploid parent cell