1. Chapter 9: Cell Reproduction Mitosis and Meiosis

2. Cell Division and Mitosis Cell division –increases the total number of cells in an organism What happens to cell division when growth stops? –Continues –New cells replace dead cells

3. Nucleus

4. The Cell Cycle What is it? –Series of cell divisions –DNA must be copied and divided exactly

5. What are we dividing? in nucleus DNA All body cells have 46! Chromosomes!

6. Chromosome Numbers Sex chromosomes –X and Y (2) Autosomes –Body chromosomes (44) Total Humans: 46

7. Turner Syndrome XO Female lacking one X chromosome Egg does not have the sex chromosome female typically sterile

8. Turner Syndrome symptoms Poor breast development Skin folds on neck Wide-spread nipples Elbow deformities Swollen ankles and feet No menstruation

9. Down Syndrome (trisomy-21) Error caused due to non-disjunction –Chromosome pairs do not separate properly during cell division

10. Downsyndrome traits? Skin folds on upper eye corners Poor muscle tone Enlarged tongue Short neck Broad and round head Flat nasal bridge

11. Klinefelter Syndrome (XXY) Extra X chromosome Male is typically sterile

12. Binary Fission Prokaryotes copy genetic information Two identical haploid cells

13. Terms: Diploid –Cells with two sets of chromosomes –2n –Body cells Haploid –Cells with one set of chromosomes –n–n –Sex cells

14. Karyotypes Pictorial spread of chromosomes Used to detect genetic abnormalities (Down Syndrome)

16. Chromosome structure Chromatin - less tightly coiled DNA

17. Chromosomes DNA coiled around histone proteins

18. Homologous Chromosomes Two copies of each autosome one from each parent –Same length –Same centromere position –Same genes

19. Mitosis- (IPMAT) Throughout life in all parts of the body, except sex cells 5 phases –Interphase (time between divisions) –Prophase –Metaphase –Anaphase –Telophase (cytokinesis)

21. Phases of the Cell Cycle Stage (in order) Description G1G1 Initial growth Increase in size & make new organelles etc. S DNA replication G2G2 Prepare for division, more growth M Nuclear (mitosis) & Cell division (cytokinesis) *G 0 Resting stage following G1 “Waits” here until it is ready to divide again Some cells cannot come out of G 0 Interphase

22. G 0 phase Cell exits cell cycle No copying of DNA No cell division –Nerve cells –Heart cells

23. Phases of the Cell Cycle S G2G2 G1G1 Checkpoints!

25. Interphase Non-dividing stage Nucleolus & nuclear membrane are visible Period of growth

26. Interphase 3 stages: –G1–G1 Period of rapid growth Cell size increase Organelles double –S–S DNA replicates –G2–G2 More growth

27. Prophase Nuclear membrane & nucleolus breakdown DNA coils into chromosomes (visible) Centrioles –Spindle fibers

28. Metaphase Chromosomes line up in the middle of the cell Spindle fibers attach to centromere

29. Anaphase Chromatids split at centromere Are considered individual Chromosomes Move to opposite poles

30. Telophase Chromosomes reach opposite ends 2 new nuclear membranes form Spindles disappear

31. Cytokinesis Division of the cytoplasm Division of organelles

32. Cytokinesis: Plants v. Animals 1.Plants: Cell plate forms and gives rise to a cell wall 2.Animals: membrane pinches in forming a cleavage furrow

33. Whitefish blastula mitosis anaphase metaphase telophase prophase interphase

34. Onion root tip mitosis anaphase metaphase telophase prophase interphase

35. Apoptosis  Programmed cell death  Cells going through apoptosis actually shrink and shrivel in a controlled process.

36. What happens when the Checkpoints don’t work? Cancer –uncontrolled growth and division of cells

37. Cancer Mutations –In genes called “oncogenes” –When 6 or 7 mutations occur = cancer Mutagens –Anything that causes cancer Environment UV rays X rays Chemicals

38. Cancer progression Metastasis

39. Angiogenesis Developing arteries and veins to “feed” the tumor

40. S G2G2 G1G1

42. Gametogenesis Gamete formation –Spermatogenesis –oogenesis

43. Fertilization Haploid gametes (n) fuse to form a diploid (2n) zygote. Sexual Reproduction 23 + 23 = 46

44. Some Meiosis differences Occurs in reproductive cells Halves the number of chromosomes Four haploid gametes are produced Two successive nuclear divisions Exchange of genetic information

45. Meiosis I

46. Interphase I Period of Growth –Same as in mitosis

47. Prophase I Spindle fibers form Crossing-over –exchange of genetic material between homologous chromosomes

48. Crossing over

49. Crossing-over results in… Genetic recombination –New mixture of genes

50. Metaphase I Homologous chromosome pairs line up at middle of cell

51. Anaphase I Homologous chromosomes migrate to opposite poles

52. Telophase I Homologous chromosomes are at opposite poles Nuclear membranes form Cytokinesis

53. Meiosis II No more replication Separates identical chromatids Produces 4 haploid (n) cells (gametes)

54. Prophase II No crossing over Spindle fibers form

55. Metaphase II Individual chromosomes line up

56. Anaphase II Sister chromatids are pulled to opposite poles

57. Telophase II Nuclear membrane forms 4 haploid (n) cells (gametes)