Cell Division Mitosis and Meiosis

1. Cell DivisionMitosis and Meiosis

2. Types of Cell Division 1) Mitosis • production of identical daughter cells • growth or replacement of body cells. • asexual reproduction. (offspring and parents are identical)

3. Types of Cell Division 2) Meiosis • production of the gametes (sex cells) • Sperm and eggs have half the genetic information • sexual reproduction

5. The Cell Cycle • 10% time dividing • 90% time interphase

6. Interphase 1) G1 (gap phase) -manufactures proteins and amino acids needed for both cell processes and cell division 2) S (synthesis phase) – DNA replicates.

7. 3) G2 (gap phase) • increases the rate of protein synthesis and prepares to divide. • grows larger

8. Division • Mitosis or Meiosis • cell can divide only about 50 times on average. • To ensure that the cells in a tissue are healthy, cells will undergo a form of cell suicide called apoptosis. • Cell Death

9. Terms • Chromatin – complex of DNA and protein that makes chromosomes • Uncondensed chromosome – long, thin strands not visible with light microscope • Condensed chromosome – short and visible

11. Chromosome vs. Chromatid • Chromosomes replicate before division to form 2 matched sister chromatids

12. Ploidy • Humans have 46 chromosomes (diploid or 2N) • Sex gametes have 23 chromosomes (haploid or N • Some organisms have polyploidy • Ex) corn – 4n (tetraploidy)

13. –same size and shape and carry the genes for the same traits, but have different details Humans have 23 homologous chromosomes for a total of 46 Homologous chromosomes

14. Gene • basic unit of heredity • sequence of nucleotide bases in DNA. • codes for a specific proteins

15. Autosomes – chromosomes that do not influence gender • Sex Chromosomes – X and Y chromosomes that determine gender in humans

16. Mitosis

17. Prophase • Early: chromatin condenses, centrioles move to poles and attach to spindle fibres • Late: spindle fibres attach to centromere, nuclear membrane dissolves

18. Metaphase • chromosomes line up on the equatorial plate

19. Anaphase • chromatids begin to separate

20. Telophase • nucleolus re-appears, nuclear membrane reforms, the chromosomes unravel to form a loose mass of chromatin, • cells undergo cytokinesis (divide cytoplasm)

21. mitosis

22. a cell plate forms between the new daughter cells the cell membrane pinches in between the two daughter cells Plant vs Animal Cells

23. Mitosis Overall • http://www.loci.wisc.edu/outreach/bioclips/CDBio.html

24. Some Methods of Asexual Reproduction 1.  Binary fission - equal division of both the organism cytoplasm and nucleus to form two identical organisms ex: Protist, amoeba 

25. 2) Budding - one parent dividing its nucleus (genetic material) equally, but cytoplasm unequally ex: Fungi-  yeast

26. Meiosis – Sexual Cell Division

27. Meiosis I – Reduction Division Prophase I – homologous chromosomes undergo synapsis (pair up) and crossing over. -tetrad

28. Metaphase I – homologous pairs line up along the equatorial plate.

29. Anaphase I – homologous chromosomes separate and are pulled to opposite poles = segregation

30. Chromosomes undergo independent assortment in during Anaphase I -increases genetic diversity

31. Telophase I – daughter cells separate, each has one chromosome from each homologous pair. -reduction has occurred so that the new cells will be haploid (n)

32. Meiosis II – like mitosis but no replication of DNA • Prophase II –spindles form

33. Metaphase II –chromosomes align at the equatorial plate

34. Anaphase II – the daughter chromatids separate and move towards separate poles

35. Telophase II – spindle fibres disappear, nuclei reform and cytokinesis takes place. (All 4 daughter cells are haploid.)

36. Meiosis

37. NOVA Online | 18 Ways to Make a Baby | How Cells Divide: Mitosis vs. Meiosis (Flash)

38. Human Life Cycle

39. Fern Life Cycle

40. Angiosperm life cycle

41. Oogenesis

42. Spermatogenesis

43. Oogenesis meiosis II completes only if egg is fertilized Secondary oocyte receives most of the cytoplasm and becomes the egg polar bodies have less cytoplasm and degenerate one egg cell is produced Spermatogenesis meiosis I and II are both completed before fertilization each sperm cell produced receives an equal share of cytoplasm flagellum forms from one of the centrioles four spermatids are produced Oogenesis vs Spermatogenesis

44. Human Karyotype Chart

45. Gender • Female is XX • Male is XY XX XY

46. Chromosomal abnormalities can be detected by doing a karyotype chart. • Fetal cells are collected through amniocentesis or chorionic villi sampling

47. Successful cell division relies on 2 things: 1. accurate replication of the chromosomes 2. exact separation / distribution of the chromosomes

48. Abnormal Meiosis • Non-disjunction – occurs during meiosis when two homologous chromosomes move to the same pole Normal Division Non-disjunction

49. Trisomy –three chromosomes replace a normal pair (47 chromosomes in humans)

50. Some Common Genetic Disorders Down’s syndrome – trisomy 21 • Extra 21 chromosome • more common in children born to women over 40 • characterized by short stature, folds to the eyelids, stubby fingers, wide gap between 1st and 3rd toes, large fissured tongue, round head, palm creases, mild to severe mental impairment.