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Cell division: mitosis and meiosis

Cell division: mitosis and meiosis

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Cell division: mitosis and meiosis

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  1. Cell division: mitosis and meiosis • Dividing cells • II. Mitosis and the cell cycle • III. Stages of mitosis • A. Prophase • B. Metaphase • C. Anaphase • D. Telophase • IV. Stem cells • V. Telomeres and telomerase • VI. Cancer cells • VII. Meiosis • VIII. Gametogenesis

  2. Binary Fission- prokaryotes

  3. Meiosis, mitosis, and the chromosome number Ploidy levels: diploid (2N) and haploid (1N) In mitosis, ploidy level is maintained In meiosis, ploidy level is halved. Human = 46 Dog = 78 Chicken = 78 Chimpanzee = 48 Record > 1000!

  4. II. Mitosis and the cell cycle 10 hours 8 hours 5 hours 1 hour

  5. If a cell, like a red blood cell, were to stop dividing, what stage of the cell cycle would be terminal for that cell? a. G1 b. G2 c. S d. mitotic If a cell that was 4N at the start of meiosis, the end result would be _______ cells . a. 1N b. 2N c. 3N d. 4N

  6. III. Stages of mitosis

  7. What is the ploidy of a cell in anaphase of mitosis? a. Haploid b. diploid c. triploid d. quatraploid In what phase do chromosomes line up at the equator? a. metaphase b. anaphase c. prophase d. telophase When attached together , what are the two replicated DNA strands of a single chromosome called? a. centromeres b. chromosomes c. chromatids d. chromatin

  8. Mitosis Mitosis animation

  9. DNA before and after mitosis

  10. IV. Stem cells Tissues without adult stem cells?

  11. Stem cell research Adult stem cell research Embryo stem cell research

  12. Stem cell potential Incompatibility, ethics, and the law Adult cell cloning

  13. IVF/ PGD and stem cell research

  14. How does the ‘PGD technique’ circumvent the ethical issues surrounding the use of embryos in stem cell research? a. it doesn’t b. embryos are not used in any way for this technique c. embryos are not destroyed d. only dead embryos are used • What is the advantage of using embryonic stem cells over other • types of stems cells? • They divide more quickly • There is less controversy in using them • They are easier to work with • They are more versatile

  15. Even with tissues derived from embryonic stem cells, patients still • face the problem of tissue incompatibility. What is one way this could • be overcome? • Use tissues derived from modified PGD • Use tissues derived from adult stem cells • Use tissues derived from cloned embryos • What is the current federal law regarding embryonic stem cell • research? • There are no restrictions • Federal funding is allowed only for research on existing lines • All embryonic stem cell research is illegal • Embryonic stem cell research is allowed on defective embryos • only

  16. V. Telomeres and telomerase TTAGGG embryos stem cells cancer cells

  17. What exactly are telomeres? • Caps at the ends of chromosomes • An enzyme that allows cells to keep dividing • A repeated sequence of nucleotides at the ends of chromosomes • Structures found only in embryos • Which of the following cells do not have telomerase? • Mature skin cells • Liver stem cells • Early embryonic cells • Cancer cells

  18. VI. Cancer A. Two types of tumors (neoplasms) B. Cancer cell anatomy and physiology 1. differentiation 2. shape 3. embryonic proliferation 4. non-programmed cell death C. Genes and cancer 1. oncogenes 2. tumor suppressing genes 3. teleomerase

  19. A. Two types of tumors (neoplasms) An inappropriate proliferation of cells Neoplasms: two types benign malignant Metastasis

  20. B. Cancer cell anatomy and physiology 1. differentiation 2. shape 3. proliferation 4. Non-programmed cell death 5. Telomerase

  21. C. Genes and cancer Stem cells, cancer, and aging Ink4 1. oncogenes 2. tumor suppressing genes 3. Telomerase genes Progression of cancer

  22. What is the problem with enhancing the activity of Ink4? • Increased risk of cancer • Speeding up of the aging process • Both a and b • Neither a or b • What are oncogenes? • Genes that regulate cell division • Genes that suppress tumors • Genes that reestablish telomeres • Mutated proto-oncogenes

  23. VII. Meiosis A. Overview 1. Homologues/ homologous pairs Why half? 2. 2 goals: reducing the chromosome number by half and shuffling (recombining) the genes

  24. Human Life Cycle

  25. Meiosis I Crossing over Meiosis II Independent Assortment

  26. Crossing Over

  27. Independent Assortment 2n = number of unique gametes

  28. Meiosis II Meiosis animation

  29. In what phases of meiosis do genetic recombination take place? • Prophase I and Prophase II • Metaphase I and Anaphase I • Prophase II and Metaphase II • Prophase I and Metaphase I If an organism has 3 pairs of chromosomes, based on independent assortment, how many genetically unique gametes would it have? a. 3 b. 6 c. 8 d. 9

  30. Problems in meiosis:aneuploidy Nondisjunction and Trisomy: Anaphase II

  31. Problems in meiosis Nondisjunction and Trisomy Women over 35, 2 to 6 times the number of mutations Implantation of embryo more likely Most common trisomy is trisomy 21 (Down Syndrome)

  32. Trisomy 21: Down syndrome Trisomy 21 karyotype

  33. Klinefelter’s Syndrome

  34. Turner Syndrome Monosomy

  35. Which of the following is the most accurate statement concerning • aneuploidy? • Nondisjunction of chromosomes during meiosis • A condition in which there are not the correct number of • chromosomes • c. Three chromosomes at position number 21 • d. The result of early implantation of the embryo • What would be the result of a nondisjunction in Anaphase I? • Two normal gametes, one with an extra chromosome, and one • missing a chromosome • b. Two normal gametes, two with an extra chromosome • c. Three gametes with a missing chromosome, one with an extra • chromosome • d. Two gametes with an extra chromosome, two with a missing • chromosome

  36. Meiosis compared to mitosis Purpose Number of cells produced Genetics of cells produced Ploidy of cells produced Where they occur Sex cells Somatic cells

  37. Meiosis compared to mitosis

  38. Meiosis compared to mitosis

  39. VIII. Gametogenesis

  40. Spermatogenesis Puberty Average sperm production = 100 million per day

  41. Oogenesis Arrested at Metaphase II Arrested at Prophase I Meiosis completed at fertilization In embryo At birth 400 released Approximately 400, 000 Ovulation

  42. When does oogenesis start in female mammals? • At birth • Before birth • At puberty • At fertilization When does oogenesis end in female mammals? a. At birth b. Before birth c. At puberty d. At fertilization

  43. In oogenesis, what is the end result of interkinesis? • Two secondary oocytes • One secondary oocyte and one polar body • One secondary oocyte and two polar bodies • Two secondary oocytes and two polar bodies

  44. Contributions of egg and sperm to embryo egg sperm 1. Haploid set of chromosomes 1. Haploid set 2. X to males and females 2. X to females; Y to males 3. Protection 4. Nourishment 5. Directions for early development 6. Mitochondria Mutations?

  45. Which of the following is a contribution of the sperm to the embryo? • Mitochondria • Directions for early development • Protection • Nourishment • Most mutations • The contribution of the sperm above is __________ . • Beneficial • Detrimental • Neutral • Could be any or all of the above

  46. The end