Biology Cellular Reproduction 1196898661945653 5


Published on

asjjsajsaj sjsj

Published in: Technology, Education
1 Comment
1 Like
  • It´s a very good presentation.
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Biology Cellular Reproduction 1196898661945653 5

  1. 1. Cell Reproduction
  2. 2. Starting at the beginning… <ul><li>Biologically speaking, where did YOU come from? </li></ul>
  3. 3. Cells <ul><li>How many cells make up a human body? </li></ul><ul><li>Did you have the same number last year? What about when you were 2 years old? 2 months old? </li></ul>
  4. 4. Cells <ul><li>Your body is made up of between 10 and 100 trillion cells. (100,000,000,000,000) </li></ul><ul><li>One-thousandth of them die every day </li></ul>
  5. 5. Cells <ul><li>Where do all these cells come from? </li></ul>
  6. 6. Cell Specialization <ul><li>Different body cells perform different functions </li></ul><ul><li>Examples: skin, nerve, red blood cells, liver cells, platelets </li></ul>
  7. 7. Cell Specialization <ul><li>Different cells live for different amounts of time </li></ul>
  8. 8. Cellular Reproduction <ul><li>New cells are made from copies of old cells </li></ul><ul><li>This process began occurring before you were born and will continue until after you die </li></ul>
  9. 9. Types of Cellular Reproduction <ul><li>MITOSIS – results in two identical cells; used for the majority of cells in the body </li></ul><ul><li>MEIOSIS – results in four cells that are different from the “parents”; used for sex cells only </li></ul>
  10. 10. Mitosis <ul><li>Results in body growth or body repair </li></ul><ul><li>Two new cells are called “daughter cells” </li></ul>
  11. 11. A Review of Cell Features <ul><li>Cell Membrane </li></ul><ul><li>Cytoplasm </li></ul><ul><li>Nucleus </li></ul><ul><li>Nuclear Membrane </li></ul><ul><li>Chromosomes – strands that carry a cell’s DNA </li></ul><ul><li>Centrioles – strong, barrell-shaped organelle </li></ul>
  12. 12. Mitosis <ul><li>Goals – duplicate chromosomes and move them to two new daughter cells </li></ul>
  13. 13. Before Mitosis Begins <ul><li>Chromosomes are duplicated within the cells (exact copies) </li></ul><ul><li>Held together at center </li></ul><ul><li>Two strands are called “sister chromatids” </li></ul>
  14. 14. Mitosis <ul><li>Step 1: PROPHASE </li></ul><ul><ul><li>Sister chromatids thicken </li></ul></ul><ul><ul><li>Nuclear membrane breaks down </li></ul></ul><ul><ul><li>Two centrioles move apart </li></ul></ul><ul><ul><li>Fibers (strands of protein) form between centrioles </li></ul></ul>
  15. 16. Mitosis <ul><li>Step 2: METAPHASE </li></ul><ul><ul><li>Centrioles to opposite ends of cell </li></ul></ul><ul><ul><li>Fibers stretch between </li></ul></ul><ul><ul><li>Sister chromatids attach to fibers </li></ul></ul><ul><ul><li>Sister chromatids line up at center of the cell </li></ul></ul>
  16. 18. Mitosis <ul><li>Step 3: ANAPHASE </li></ul><ul><ul><li>Sister chromatids pulled apart from partner </li></ul></ul><ul><ul><li>Fibers pull chromatids towards centrioles at opposite ends of the cell </li></ul></ul>
  17. 20. Mitosis <ul><li>STEP 4: TELOPHASE </li></ul><ul><ul><li>Each side now has complete set of chromosomes </li></ul></ul><ul><ul><li>Fibers disappear </li></ul></ul><ul><ul><li>Nuclear membrane re-forms </li></ul></ul><ul><ul><li>Cell membrane pinches inwards to form 2 cells </li></ul></ul>
  18. 22. Mitosis in Plant Cells <ul><li>2 Differences </li></ul><ul><ul><li>No centrioles </li></ul></ul><ul><ul><li>Cell wall must re-form between new cells </li></ul></ul>
  20. 24. Importance of Chromosomes <ul><li>All chromosomes come in pairs </li></ul><ul><li>Humans have 23 pairs, so a normal cell has 46 chromosomes </li></ul><ul><li>All cells need a full set to function properly (except sex cells) </li></ul>
  21. 25. Chromosome Number <ul><li>Before mitosis begins, cells have two of each chromosome (2N) </li></ul><ul><li>After chromosomes duplicate, cells have four of each chromosome (4N) </li></ul><ul><li>After mitosis, cells have two of each chromosome (2N) </li></ul>
  22. 26. Meiosis
  23. 27. Meiosis <ul><li>Process that creates gametes (eggs and sperm) </li></ul><ul><li>Cells divide twice </li></ul>
  24. 28. Chromosome Number <ul><li>Cells start with two of each chromosome (2N) </li></ul><ul><li>Chromosomes double (4N) </li></ul><ul><li>Pairs divide (2N) </li></ul><ul><li>Sister chromatids divide (N) </li></ul>
  25. 29. Importance of Meiosis <ul><li>During fertilization, sperm (N) and egg (N) fuse to create one cell (2N) </li></ul><ul><li>New cell has complete set of chromosomes (half from mother, half from father) </li></ul>
  26. 30. Chromosome Number <ul><li>N represents number of PAIRS of chromosomes </li></ul><ul><li>2N = total number of chromosomes in a normal cell </li></ul><ul><li>N – total number of chromosomes in a gamete (sex cell) </li></ul>
  27. 31. Steps of Meiosis <ul><li>Step 1 </li></ul><ul><ul><li>PROPHASE I </li></ul></ul>
  28. 32. Steps of Meiosis <ul><li>Step 2: </li></ul><ul><ul><li>METAPHASE I </li></ul></ul>
  29. 33. Steps of Meiosis <ul><li>Step 3: </li></ul><ul><ul><li>ANAPHASE I </li></ul></ul><ul><ul><ul><li>Sister chromatids DO NOT separate. </li></ul></ul></ul><ul><ul><li>TELEPHASE I </li></ul></ul>
  30. 34. Steps of Meiosis <ul><li>Step 4: </li></ul><ul><ul><li>PROPHASE II </li></ul></ul><ul><ul><li>Cell has been split in two </li></ul></ul><ul><ul><li>No nuclear membrane forms </li></ul></ul>
  31. 35. Steps of Meiosis <ul><li>Step 5: </li></ul><ul><ul><li>Occurs in both cells </li></ul></ul><ul><ul><li>METAPHASE II </li></ul></ul>
  32. 36. Steps of Meiosis <ul><li>Step 6: </li></ul><ul><ul><li>ANAPHASE II </li></ul></ul><ul><ul><li>TELEPHASE II </li></ul></ul>
  33. 37. THE MOST IMPORTANT DIFFERENCE <ul><li>In the first cell division, CHROMOSOME PAIRS are pulled apart. </li></ul><ul><li>In the second cell division, SISTER CHROMATIDS are pulled apart. </li></ul>
  34. 38. Cancer and Aging
  35. 39. Cancer/Aging <ul><li>How are cancer and aging similar? </li></ul>
  36. 40. Cancer/Aging <ul><li>Changes in rates of mitosis </li></ul>
  37. 41. Aging <ul><li>What properties of a person’s body change as they age? </li></ul><ul><li>Physically? Physiologically? </li></ul>
  38. 42. Cancer <ul><li>Rapid, abnormal, uncontrolled mitosis </li></ul><ul><li>What causes cancer? </li></ul>
  39. 43. Cancer Causes <ul><li>Viruses </li></ul><ul><li>Chemicals </li></ul><ul><li>Radiation </li></ul>