Biology - Chp 10 - Cell Growth And Reproduction - PowerPoint


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Biology - Chp 10 - Cell Growth And Reproduction - PowerPoint

  1. 1. Chapter 10Cell Growth and Reproduction
  2. 2. The Big Idea• You are constantly changing• Worn out cells get replaced• Cuts and bruises heal• 2-3 billion red blood cells get replaced each second• Muscles you exercise get larger
  3. 3. The Cell Cycle Cell DivisionPreparing forreproduction Interphase Growth and Development
  4. 4. 10-1 Cell Growth
  5. 5. Q: When a living thing grows, what happens to its cells?A: Cells increase in number
  6. 6. There are two main reasons why cells divide1. The larger the cell becomes, the more demands there are on the DNA2. The cell has trouble moving enough nutrients and wastes across the cell membrane
  7. 7. Division of a cell• Before it gets too large, a growing cell divides forming two daughter cells• The process by which a cell divides into two new daughter cells is called cell division
  8. 8. Daughter cells
  9. 9. This solves the two problems of a growing cell1. The cell replicates all of its DNA2. The actual division of the cell decreases its volume
  10. 10. 10-2 Cell Division
  11. 11. In eukaryotes cell division occurs in two main stages1. Mitosis2. Cytokinesis
  12. 12. Chromosomes• In eukaryotic cells, the genetic information that is passed on from one generation to the next is carried on Chromosomes ___________________________
  13. 13. • Chromosomes are made of DNA – which carries the cells coded information – and proteins• The cells of every organism have a specific number of chromosomes• You can’t see chromosomes except during cell division, when they condense and compact
  14. 14. • Before cell division, each chromosome is replicated, or copied• Because of this, each chromosome consists of two identical _______________________________ “sister chromatids”• When the cell divides, the sister chromatids separate and one chromatid goes to each of the two new cells• Each pair of chromatids are attached at an area called the centromere
  15. 15. Interphase• “In-between” period of growth between division
  16. 16. • During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again• The cell cycle consists of 4 phases1. M phase2. G1 phase3. S phase4. G2 phase
  17. 17. • G1 – Cells do most of their growing. They increase in size and make new proteins and organelles• S – Chromosomes are replicated• G2 – Organelles and molecules required for cell division are produced• M – cell divides
  18. 18. Prophase • The chromatin condenses into chromosomes • The centrioles separate • A spindle begins to form • The nuclear membrane breaks down
  19. 19. Metaphase • Chromosomes line up down the middle of the cell • Each chromosome is connected to a spindle fiber at its centromere
  20. 20. Anaphase • Centromeres split, allowing sister chromatids to separate • The chromosomes move to opposite ends of the cell
  21. 21. Telophase • Chromosomes unwind • A nuclear membrane reforms • Nucleolus becomes visable
  22. 22. Cytokinesis (In animals…)
  23. 23. Cytokinesis (In plants)• A cell plate gradually develops into a separating membrane• A cell wall then begins to appear in the cell plate
  24. 24. Golgi vesiclesmove towardequator Early cell plate Cell Plate
  25. 25. The Big Picture!• Mitosis is the division of a nucleus ___________• Mitosis produces two nuclei that have the __________ number of same chromosomes as the original
  26. 26. (Before Mitosis) 4646 46 (After Mitosis)
  27. 27. 10-3 Regulating the Cell Cycle
  28. 28. Knowing When to Stop•Suppose you had a paper cut on yourfinger. Although the cut may have bled andstung a little, after a few days, it will havedisappeared, and your finger would be asgood as new.1. How do you think the body repairs an injury, such as a cut on a finger?2. How long do you think this repair process continues?3. What do you think causes the cells to stop the repair process?
  29. 29. Controls on Cell Division
  30. 30. Controls on Cell Division• When cells come into contact with other cells, they respond by not growing• When an injury such as a cut occurs, cells at the edges of the injury are stimulated to divide rapidly, the cell division stops when the healing process is complete
  31. 31. The sample is injected into a second cell in G2 of interphase.A sample of cytoplasm isremoved from a cell in As a result, themitosis. second cell enters mitosis.
  32. 32. Cyclins• Protein that regulates the cell cycle• There are 2 types of regulatory proteins; those that occur inside the cell and those that occur outside the cell.
  33. 33. Internal Regulators• Allow the cell cycle to proceed only when certain processes have happened inside the cell• Ex.) several regulatory proteins make sure that a cell does not go through mitosis until all chromosomes have been replicated
  34. 34. External Regulators• Direct cells to speed up or slow down the cell cycle• Ex.) growth factors• Molecules found on the surface of neighboring cells often have the opposite effect causing cells to slow down or stop their cell cycles• These signals prevent excessive cell growth
  35. 35. Cancer• A disorder in which some of the body’s own cells lose the ability to control growth• When cells divide uncontrollably, masses of cells called tumors can damage the surrounding tissues• Cancer cells may break loose from the tumors and spread throughout the body*(DNA interactive DVD)*
  36. 36. Q: What causes the loss of growth control?A: smoking tobacco, radiation and chemical exposure, viral infectionsAll cancers have one thing in common: The control over the cell cycle has been broken• Some cancer cells will no longer respond to external growth regulators• Others fail to produce the internal regulators
  37. 37. p53• An astonishing number of cancer cells have a defect in a gene called p53• p53 normally halts the cell cycle until all the chromosomes have been properly replicated• if we could fix p53 we could cure many forms of cancer
  38. 38. Is a cure in sight?• Cancer is a serious disease• As difficult as a cure would be, at least scientists know where to start• Cancer is a disease of the cell cycle , and conquering cancer will require a much deeper understanding of the processes that control cell division