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Today

Today. Pick up your test folder on the back counter Think about questions you have on the multiple choice. Grades This Unit. Ch. 12 reading guide Ch. 13 reading guide Mitosis/Meiosis diagrams Mitosis and meiosis lab Cancer Research page Unit 6 Exam. What we have left this semester.

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Today

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  1. Today • Pick up your test folder on the back counter • Think about questions you have on the multiple choice

  2. Grades This Unit • Ch. 12 reading guide • Ch. 13 reading guide • Mitosis/Meiosis diagrams • Mitosis and meiosis lab • Cancer Research page • Unit 6 Exam

  3. What we have left this semester • Unit 6 – Cell Division • Unit 7 – Genetics • Unit 8 – DNA/protein synthesis

  4. Objectives • Mitosis and meiosis comparison • Look at the steps of the cell cycle • Look at the steps of mitosis

  5. Mitosis/Meiosis

  6. MITOSIS 2N 2N 2N ALL CELLS AND DNA IDENTICAL

  7. Mitosis • Occurs in Somatic (body) cells • Used in growth & repair of body cells, Asexual reproduction

  8. Asexual Reproduction • Exact copies of parents • Mitosis • Clones • Ex. Budding, Fragmentation

  9. Starts with • Parent cell – (Diploid - 2N) – has both sets of chromosomes

  10. Ends with • 2 identical diploid daughter cells

  11. Cells will turn into this • Daughter cells will turn into fully functional body cells (liver cells, muscle cells, etc.)

  12. Chromosome Number • Stay the same (46 chromosomes in humans)

  13. Genetic material • Stays the same (identical)

  14. Problems • Uncontrolled growth or division causes cancer

  15. Meiosis 2N Division I Division II 1N 1N 1N 1N 4 NEW GENETICALLY DIFFERENT CELLS

  16. Meiosis • Occurs in Gametes (sex cells) • Used in Sexual reproduction

  17. Sexual Reproduction • Produces unique combination of genes • Genetic Variation • Can aid in survival of species

  18. Starts with • Diploid cell (2N)

  19. Ends with • 4 Haploid (1N) cells – 1 set of chromosomes • Called a Reduction division (2N to 1N)

  20. Cells will turn into this • Males – 4 sperm • Females – 1 egg and 3 polar bodies

  21. Chromosome Number • Divides in half (46 to 23 chromosomes) • Sperm (23) and egg (23) combine to form a zygote (46) during fertilization • This ensures chromosome # is right

  22. Genetic material • Genetic Variation caused by crossing over – chromatids overlap, break apart, and reattach to form new combinations of DNA

  23. Problems • Zygotes with wrong chromosome # usually will not survive

  24. Chapter 12~ The Cell Cycle

  25. Why do cells divide? • Growth and repair • Sexual reproduction • They get too big • Density of cells around them

  26. Why do cells divide?

  27. Why do cells divide? • The surface area-to-volume ratio gets too small • Nutrients and waste cannot be transported in and out efficiently • The genome-to-volume ratio gets too small • DNA cannot make enough proteins/enzymes to control (regulate) the rest of the cell

  28. Cell Cycle • Order • Interphase • Checkpoints

  29. The Cell Cycle DNA Copied Cells prepare for Division Cells Mature Daughter Cells Cell Divides into Identical cells

  30. The Cell Cycle • Interphase (90% of cycle)• G1 phase~ growth • S phase~ synthesis of DNA • G2 phase~ preparation for cell division • Mitotic phase • Mitosis~ nuclear division • Cytokinesis~ cytoplasm division

  31. Cell Division: Key Roles • Genome: cell’s genetic information • Somatic (body cells) cells • Gametes (reproductive cells): sperm and egg cells • Chromosomes: DNA molecules • Diploid (2n): 2 sets of chromosomes • Haploid (1n): 1 set of chromosomes • Chromatin: DNA-protein complex • Chromatids: replicated strands of a chromosome • Centromere: narrowing “waist” of sister chromatids • Mitosis: nuclear division • Cytokinesis: cytoplasm division • Meiosis: gamete cell division

  32. Chromosome Centromere DNA Replication Sister Chromatids

  33. MITOSIS CYTOKINESIS

  34. Homologous chromosomes made up of sister chromatids joined at thecentromere.

  35. Haploid– 1 copy of each chromosomeDiploid– 2 copies of each chromosome (known as homologous chromosomes)

  36. Replicated homologous chromosomes Unreplicated homologous chromosomes Centromere

  37. Karyotype • A picture of the chromosomes from a human cell arranged in pairs by size • First 22 pairs are called autosomes • Last pair are the sex chromosomes • XX female or XY male

  38. Four Mitotic Phases • Prophase • Metaphase • Anaphase • Telophase

  39. Prophase • Chromosomes visible • Nucleoli disappear • Sister chromatids present • Mitotic spindle forms • Centrosomes move • Nuclear membrane fragments • Spindle interaction with chromosomes • Kinetochores develops

  40. Metaphase • Centrosomes at opposite poles • Centromeres are aligned • Kinetochores of sister chromatids attached to microtubules (spindle)

  41. Anaphase • Paired centromeres separate; sister chromatids liberated • Chromosomes move to opposite poles • Each pole now has a complete set of chromosomes

  42. Telophase • Daughter nuclei form • Nuclear envelopes arise • Chromatin becomes less coiled • Two new nuclei complete mitosis

  43. DIPLOID MICROTUBULES

  44. DIPLOID Sister Chromatids separate

  45. Cytokinesis • Cytoplasmic division • Animals: cleavage furrow • Plants: cell plate

  46. Cytokinesis 15. Cleavage furrow in animal cell 16. Cell plate in plant cell

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