Mitosis/Meiosis

1. Mitosis/Meiosis

2. Cell Growth • Reason: • Large cells create more of a demand on DNA • Trouble moving enough nutrients and wastes across cell membrane

3. Importance: cells regenerate • Repair/renew • Growth • reproduction

4. Reproduction • Asexual • 1 parent • Simple cell division- cells duplicate genetic material, splits into 2 new identical offspring • Ex: Paramecium, sea stars

5. Sexual Reproduction • 2 parents • Genetic material combine- offspring differ from parents • Union of sex cells (egg + sperm) • Ex: multicellular organisms, single celled organisms

6. 2 types of cell division • Mitosis • Meiosis

7. Cell Cycle • Chromatin- fibers containing protein + DNA • Chromosomes- chromatin condensed into visible structures - thousands of genes • Ex: Humans= 46 chromosomes

9. Before cell division- chromosomes duplicate • Sister chromatids- identical copies joined • Centromere- joins chromatids

10. Cell Cycle • Birth of cell till time it reproduces • Interphase (90%) • G1 (gap) • S phase (synthesis) • G2 • M Phase (mitotic) • Cytokinesis

11. Cytokinesis- cytoplasm divides • (1 nucleus, cytoplasm, plasma membrane)

12. Cytokinesis in Animal Cells

13. Cytokinesis in a Plant Cell

14. Mitosis • http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related • Spindle- microtubules that guide movement of chromosomes • Centrosomes- spindles grow from here • Contain centrioles in animal cells

15. Draw stages of mitosis • Pg 246-247 • Draw each stage of mitosis, the drawing should be neat and in color • Label each phase and include a detailed description of what is occurring in each • Label • Centrioles - spindle • Chromatin - centromere • Chromosomes - sister chromatids • Nuclear envelope

16. Prophase • chromatin condenses into chromosomes • Nuclear envelope breaks down • Mitotic spindle forms • Centrioles move to opposite sides of the cell

17. Metaphase • Chromosomes line up across center of cell • Chromosomes attached to spindle fibers by centrioles

18. Anaphase • Sister chromatids separate • Move toward poles by spindles, microtubules shorten • Microtubules also lengthen and push poles apart

19. Telophase • Chromosomes reach poles of spindle • Spindles disappear • 2 nuclear envelopes reform • Chromosomes uncoil and lengthen

20. Mitosis in a Whitefish

21. Mitosis in Animal Cells

22. Mitosis in a Plant Cell

23. Tumors and Cancer • Out of control cell reproduction = mass of cells or tumor • Benign Tumor • Removable by surgery • Cells remain at original site

24. Malignant Tumor- masses of cells from reproduction of cancer cells • Cancer- disruption of cell cycle • Metastasis- spread of cancer cells beyond original site

26. Cancer Treatment • Removed by surgery • Radiation therapy- high energy radiation disrupts cell division • Chemotherapy- drugs which disrupts cell division

27. Meiosis • Cell division= 4 cells each • ½ the number of chromosomes as parent • Occurs in sex organs

28. Karyotypes- display of chromosomes • Each with twin that resembles size + shape • Inherit one chromosome of each pair from mother and father= Homologous chromosome

30. Homologous Chromosome • same sequence of genes • Control same inherited characteristics • Ex: eye color gene located on same place of the homologous chromosomes but one gene may call for blue the other brown

31. Humans- 23 homologous chromosomes • Females • Males • Sex chromosomes • Male XY • Female XX

32. Diploid (2n)- 2 homologous sets of chromosomes • Haploid (n)- single set of chromosomes, produced by meiosis n = 23 2n =46 2(23)=46 Fertilization- haploid cells fuse (egg + sperm) Zygote- fertilized egg - diploid

33. Spermatogenesis- making sperm cell – all four cells develop into sperm • Oogenesis –making an egg cell=one egg

35. Process of Meiosis • Life cycles of all sexual reproducing organisms alter haploid and diploid stages • Keeps chromosome # from doubling every generation • Exchange of genetic material b/w homologous chromosomes

36. 2 meiotic division • Meiosis I- homologous chromosomes separated • Meiosis II- sister chromatids are separated into haploid cells

37. Prophase I • HC stick together = 4 chromatids (tetrad) • Spindle attaches to tetrad • Crossing over- sister chromatids exchange material

38. Metaphase I • tetrads move to middle of cell and line up

39. Anaphase I • HC separate and move to opposite ends

40. Telophase I and Cytokinesis • Chromosomes arrive at opposite poles • Nuclear envelope begins to form • Cytokineses occurs forming 2 haploid cells

41. Prophase II • spindle forms and attaches to centromeres

42. Metaphase II • chromosomes line up in center

43. Anaphase II • sister chromatids separate and move to opposite poles

44. Telophase II and Cytokinesis • Chromatids considered individual chromosomes arrive at opposite poles • Cytokinesis splits cells • Produce 4 haploid daughter cells

45. Genetic Variation • Assortment of chromosomes- happens by chance • Formula for different combinations - 2ⁿEx: Humans 2²³ = 8 million possible combos • Crossing Over- exchange of genetic material between homologous chromosomes • Occurs during prophase • Genetic recombination