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9.1 All cells come from cells

Explore the fascinating world of cell division, from growth to repair and reproduction. From chromosomes and the cell cycle to mitosis and cancer, discover the essential roles cells play in the human body and beyond.

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9.1 All cells come from cells

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  1. 9.1 All cells come from cells

  2. I. Repair and Growth • The outermost layer of your skin is actually a layer of dead cells • Underneath the outer layer is a layer of living cells that are constantly reproducing and moving outward to replace the dead cells that have been rubbed off

  3. Skin cells

  4. Repair and growth C. Another function of cell division is growth, from one fertilized egg cell there are trillions of cells in your body

  5. Cell Sizes Largest - Egg Cell (35 microns) Smallest - Sperm cell (3 microns)

  6. II. Reproduction • Cell production of new cells can result in growth and repair within organisms, cell division also has an essential role in the reproduction of entire organisms B. Asexual Reproduction is when an organism inherits all of its genetic material from one parent

  7. Repair and growth C. Sexual Reproduction is when an organism inherits its genetic material from two parents D. All multicellular organisms depend on cell division for growth

  8. Planaria • Fragmentation • Dropping tails • Penis fencing

  9. Sponges • Broadcasting • Budding and gemmules

  10. Hermaphrodite Hermaphrodite- organism that possesses both sex organs. Not to be confused with sexual preferences: Heterosexual, Homosexual, Bisexual, etc.

  11. 9.2 The cell cycle multiplies cells

  12. I. Chromosomes and Cell Division A. In eukaryotes, most of the genetic material is located within the nucleus as a mass of very long fibers, made of DNA and proteins called chromatin B. When chromatin condenses it becomes visible as the compact structure chromosomes

  13. Chromosomes and cell division C. Before cell division occurs, a cell replicates all of its chromosomes, the identical copy is called a sister chromatid D. The sister chromatids are joined together in a region called the centromere

  14. DNA to Chromosome

  15. Chromosomes

  16. Ligers and Mules

  17. Chromosomes in organisms • Chromosome numbers vary by organism • Chromosomes come in different sizes

  18. Number of Chromosomes • Diploid (2n) number of chromosomes from both parents • Haploid (n) number of chromosomes from one parent • Karyotype- visual layout of all a person’s chromosomes

  19. Karyotype XY- male XX- female

  20. Amniocentesis- what and why?

  21. II. The Cell Cycle • Cells that divide undergo an orderly sequence of events known as the cell cycle, which is from the “birth” of the cell to the time it reproduces itself

  22. Interphase • Accounts for about 90% of the cell cycle • Cell grows – G1 phase (Gap) • Rapid growth • Chromosomes uncoil • Make more organelles and cytoplasm • Cell stops growing - G0(rest) • Cell death or cells like muscle or neurons

  23. Interphase • DNA duplicates – S phase (Synthesis) • DNA is copied • Form identical sister chromatids • Cell prepares to divide – G2 phase • Centrioles (Cylinders that separate cells) replicate • Chromosomes shorten and thicken • Organelles finished being made

  24. Cell Cycle

  25. 9.3 Cells divide during mitotic phase

  26. Greatest Discoveries: Mitosis

  27. Mitosis

  28. I. Mitosis • During mitosis, the chromosomes movements are guided by a football-shaped framework of microtubles called the spindle • The spindle microtubles grow from two centrosomes, the regions that contain the centrioles

  29. Mitosis • Interphase – The cell is making molecules and organelles and has duplicated its DNA • Prophase – The chromatin fibers have condensed into chromosomes and pair up with their sister chromatids. The spindle forms, nuclear envelope and nucleoli disappear • Metaphase – All the chromosomes gather in the middle of the cell • Anaphase – Sister chromatids separate from their partners

  30. Mitosis • Telophase and Cytokinesis – Chromosomes reach the poles of the spindle. The processes of prophase are reversed. Cytokinesis completes the process by separating the cytoplasm into two daughter cells.

  31. Cytokinesis in animals and plants A. Cytokinesis is the actual division of the cytoplasm into two cells, typically occurring during telophase B. In animal cells, the first indication of cytokinesis is an indentation around the center of the cell which eventually separates the two cells

  32. Cytokinesis in animals and plants C. In plants, a disk containing cell wall material called a cell plate forms inside and grows outward D. Eventually the new piece of the cell wall divides the cell in two

  33. Mitosis Video

  34. 9.4 Cancer cells grow and divide out of control

  35. I. Tumors and Cancer • An abnormal mass of normal cells is called a benign tumor B. Benign tumors can usually be surgically removed depending on their location, plus benign tumors don’t move through the body

  36. Tumors and cancer C. Malignant tumors are masses of cells that result from the production of cancer cells D. Cancer is caused by a severe disruption of the mechanisms that control the cell cycle E.. The spread of cancer cells beyond their original site is called metastasis

  37. II. Cancer Treatment A. When possible malignant tumors are removed by surgery B. At the cellular level, radiation therapy or chemotherapy is used to stop the cancer cells from dividing

  38. Cancer treatment C. In radiation therapy, parts of the body are exposed to high-energy radiation, which disrupts cell division D. Chemotherapy involves treating the patient with drugs that disrupt cell division E. Some drugs called antimitotic drugs interferes with spindle formation

  39. Cancer treatment F. Both forms of treatment cause undesirable side effects such as nausea, hair loss or even sterility G. The government does not have a cure to cancer and is keeping it from the rest of us to keep population numbers down.

  40. Greatest Discoveries: Genetics of Cancer

  41. Cancer at Bay

  42. Great Discoveries: Meiosis

  43. 9.5 Meiosis functions in sexual reproduction

  44. I. Homologous Chromosomes A. Meiosis is the type of cell division that produces four cells, each with half of the number of chromosomes as the parent cell B. Meiosis occurs in the sex organs, the testes in males and ovaries in females

  45. Homologous chromosomes C. Almost all cells have the same number and types of chromosomes D. A display of all 46 chromosomes of an individual is called a karyotype

  46. Homologous chromosomes E. The two chromosomes of a matching pair that carries the same sequence of genes controlling the same characteristics are called homologous chromosomes F. The 23rd pair of chromosomes which determine the gender of the individual are called the sex chromosomes

  47. Homologous chromosomes

  48. II. Diploid and Haploid Cells A. Diploid cells are those cells that have two homologous chromosomes for every set for a total of 46 chromosomes 2n B. Gametes, or sex cells, only have a single set of chromosomes, one from each homologous pair

  49. Diploid and haploid cells C. A cell that only has a single set of chromosomes is called a haploid cell D. Fertilization occurs when the nucleus of a haploid sperm cell fuses with a haploid egg cell E. The result of fertilization is called a zygote which is a diploid cell

  50. Number of chromosomes

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