Meiosis

Phases of Meiosis

1. Cell Division: Meiosis Prepared by: Ms. Jasmine Nikki M. Versoza

2. What are the phases of meiosis? What type of cells are made during meiosis? How many chromosomes do sperm cells have? How about egg cells? In what phase does crossing over happens? What happens during the crossing over of chromosomes? What causes the variety in genes? QUESTIONS

3. The union of two sex cells that contain one set of chromosome each and comes from two individual organisms Fertilization

4. If the reproductive cycle is to continue, then the diploid cell must reduce its number of chromosome sets before fertilization , or there will be a continual doubling to fertilization in the number of chromosome sets in every generation. Fertilization

5. The number of sets of chromosomes in a cell Haploid and Diploid Ploidy Level

6. The type of cell division taking place in sex cells . It results in haploid chromosome number. MEIOSIS

7. Reduction stage Synapsis , Crossing over, and Independent Assortment happens during this stage MEIOSIS I

8. Prophase I Metaphase I Anaphase I Telophase I MEIOSIS I

9. First mechanism that introduces variation into the gametes happens here Synapsis and Crossing Over PROPHASE I

10. Pairing of the homologous chromosomes Homologous chromosomes have the same length, staining pattern, and centromere position A paired homologous chromosome is composed of four sister chromatids known as tetrad. SYNAPSIS

11. Process wherein homologous chromatids exchange genetic material to ensure variety in gamete formation CROSSING OVER

12. The tetrads line up along the metaphase plate or equatorial plate of the cell Spindle fiber increase in number METAPHASE I

13. The second mechanism that introduces gamete variation happens here Independent or Random Assortment – the arrangement of the tetrads at the metaphase plate is at random METAPHASE I

14. Homologous chromosomes separate and migrate toward their respective poles In humans, since there are 46 chromosomes, 23 will move to the poles, which means that only half of the number of chromosomes will remain in each cell ANAPHASE I

15. The two daughter cells are completely divided An equal amount of chromosomes are found in both cells A nuclear envelope and nuclei reappear and the chromosomes become less visible TELOPHASE I

16. Why is meiosis I called the reduction stage? The ploidy level has been reduced from two to one MEIOSIS I

17. A short pause between meiosis I and meiosis II No replication of the chromosomes happen here INTERKINESIS I

18. Division stage. Produces four genetically unique cells More analogous to mitosis MEIOSIS II

19. The division of the two daughter cells with haploid chromosome numbers produced in meiosis I MEIOSIS II

20. Prophase II Metaphase II Anaphase II Telophase II MEIOSIS II

21. What are the phases of meiosis? What type of cells are made during meiosis? How many chromosomes do sperm cells have? How about egg cells? In what phase does crossing over happens? What happens during the crossing over of chromosomes? What causes the variety in genes? QUESTIONS

22. COMPARING MITOSIS AND MEIOSIS LET’S DO THIS!

23. Meiosis Prophase I (2N) Mitosis Prophase (2N) XX XX XX X X X X X X X - chromosome

24. Meiosis Metaphase I (2N) Mitosis Metaphase (2N) X - chromosome XX XX XX X X X X X X

25. X X X Meiosis Anaphase I (2N) Mitosis Anaphase (2N) X - chromosome X X X < > < < < < < > > > > > <

26. X X X Meiosis Telophase I (2N) Mitosis Telophase (2N) > < < < < < X - chromosome X X X < > > > > >

27. Meiosis Cytokinesis I (N) Mitosis Cytokinesis (2N) X - chromosome XX X XX X < < < < < < < < < < < <

28. MITOSIS: PARENT CELL VS. DAUGHTER CELLS CHECK THIS OUT:

29. Mitosis Prophase (2N) Mitosis Cytokinesis (2N) X X X X X X X - chromosome < < < < < < < < < < < <

30. Meiosis II GOING BACK…

31. X X X X X X Meiosis Prophase II (N) X - chromosome

32. Meiosis Metaphase II (N) X - chromosome X X X X X X

33. Meiosis Anaphase II (N) X - chromosome > < < < > > > < < < > >

34. X - chromosome > < < < > > Meiosis Telophase II (N) > < < < > >

35. X - chromosome < < < < < < Meiosis Cytokinesis II (N) < < < < < <

36. MEIOSIS: PARENT CELL VS. DAUGHTER CELLS CHECK THIS OUT:

37. Meiosis Prophase I (2N) Meiosis Cytokinesis II (N) X - chromosome < < < < < < < < < < < < XX XX XX

38. Why does meiosis result in haploid chromosome numbers for each daughter cell? HMMM….

39. Meiosis Prophase I (2N) Meiosis Cytokinesis II (N) X - chromosome < < < < < < < < < < < < XX XX XX

40. EVEN IF THE CHROMOSOMES OF THE FOUR DAUGHTER CELLS IN MEIOSIS DUPLICATE DURING S PHASE, IT WILL STILL RESULT IN HAPLOID CHROMOSOME NUMBER. How come the parent cell has a diploid chromosome number? HMMM….

41. PRACTICE EXERCISES If n=4 for fruit flies, how many chromosome does a wing cell have? If the 2n= 86 for a pine tree, how many chromosomes does it have in its ovum?

42. ENSURING YOUR MASTERY Complete the table below. Mitosis Meiosis Number of Daughter Cells Number of Cell Division Happening Type of cell where it is taking place Ploidy Level (Before) Ploidy Level (After)