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Cell Division Cancer

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Cell Division Cancer

  1. 1. MITOSIS The nature of replicating cells 100’s of free ppt’s from www.h i-dentfinishingschool.blogspot.com dr shabeel pn
  2. 2. Reproduction: Not as simple as it looks.
  3. 3. Reproduction presents a major problem for cells and organisms: (how can information be transmitted faithfully to progeny) I II III IV = one bit of genetic information
  4. 4. = one bit of genetic information The information transfer problem becomes more challenging as more bits of information are incorporated into the organism
  5. 5. One of life’s solutions to this challenge: “Package” the bits of information into single units called chromosomes = one bit of genetic information
  6. 6. chromosomes Packaging of genetic material in prokaryotes and eukaryotes prokaryote cell eukaryote cell
  7. 7. Fig 2.4 The structure of a highly condensed, replicated chromosome. © 2003 John Wiley and Sons Publishers
  8. 8. A Chromosome
  9. 9. BASIC GENETICS <ul><li>Each cell in the human body contains two sets of 2 3 chromosomes </li></ul><ul><li>Mitosis identically replicates this information </li></ul><ul><li>E ach cell therefore has the same </li></ul><ul><li>genetic material </li></ul><ul><li>R eproductive cells only have </li></ul><ul><li>one set of chromosomes. T hese </li></ul><ul><li>combine to make a new person </li></ul><ul><li>with different genetic material to </li></ul><ul><li>both parents </li></ul>
  10. 10. The cell cycle. © 2003 John Wiley and Sons Publishers
  11. 11. The S tages of the C ell C ycle Mitosis interphase G1 S G2 Cell division M
  12. 12. M stage <ul><li>Mitotic Stage </li></ul><ul><li>T he nucleus and cytoplasm </li></ul><ul><li>split to make two new cells </li></ul><ul><li>known as DIPLOID cells </li></ul>
  13. 13. Every dividing tissue cell in the body is always at a stage of the cell cycle. Whether it is at :- STAGES OF MITOSIS Cytokinesis Diagram showing the Stages of Mitosis Prophase Metaphas e Anaphase Telophase Interphase Th us enabl ing the body to continuously make new body tissue for growth and repair .
  14. 14. Prophase Metaphase Anaphase Telophase The Stages of M itosis Interphase
  15. 15. The Spindle <ul><li>A spindle is a web type structure made up of microtubule fibres. It is essential for mitosis because it arranges the chromosomes into their correct positions in preparation for cell division. </li></ul>Mitotic centre Microtubule A cell at metaphase a spindle
  16. 16. Chromosomes attached to spindle during nuclear division
  17. 17. INTERPHASE <ul><li>After a cell has divided, the two </li></ul><ul><li>new cells begin the process again, </li></ul><ul><li>the cell s at this stage are in </li></ul><ul><li>Interphase. </li></ul>Cell cycle It is divided into three mini stages :- <ul><li>G1 </li></ul><ul><li>S </li></ul><ul><li>G2 </li></ul>
  18. 18. Eukaryotic chromsome replicating
  19. 19. PROPHASE <ul><li>The chromatin (unravelled DNA) in the nucleus, condenses to form pairs of chromosomes. </li></ul><ul><li>The centrioles move to opposite </li></ul><ul><li>ends of the nucleus. </li></ul><ul><li>As this is happening the nucleolus </li></ul><ul><li>begins to break down </li></ul><ul><li>Nuclear membrane begins to break down </li></ul>
  20. 20. Prophase <ul><li>Chromatin condenses (remember that chromatin/DNA replicate during Interphase), the nuclear envelope dissolves, centrioles (if present) divide and migrate, the spindle forms. </li></ul>
  21. 21. METAPHASE <ul><li>The spindle becomes fully developed </li></ul><ul><li>The nuclear membrane has completely gone </li></ul><ul><li>The chromatid pairs </li></ul><ul><li>place themselves </li></ul><ul><li>onto individual fibres </li></ul><ul><li>and are aligned along </li></ul><ul><li>the centre of the </li></ul><ul><li>spindle </li></ul>
  22. 22. ANAPHASE <ul><li>The chromatid pairs are split into two </li></ul><ul><li>(This is done by movement of the spindle fibres) </li></ul><ul><li>The pairs then travel to opposite ends of the spindle </li></ul><ul><li>The halved chromatids are now called chromosomes </li></ul>
  23. 23. TELOPHASE Two new nuclei are formed when the chromosomes reach the opposite poles of the cell The nuclear membrane is formed- the nucleolus reappears The chromosomes disperse in the nucleus
  24. 24. REMEMBER! <ul><li>I nterphase </li></ul><ul><li>P rophase </li></ul><ul><li>M etaphase </li></ul><ul><li>A naphase </li></ul><ul><li>T elophase </li></ul>IPMAT
  25. 29. Mitosis in animal cells. © 2003 John Wiley and Sons Publishers
  26. 31. CYTOKINESIS <ul><li>Literally means, division of the </li></ul><ul><li>cytoplasm </li></ul><ul><li>M itosis is the splitting of the nucleus. </li></ul><ul><li>Cytokinesis is the splitting of cytoplasm </li></ul><ul><li>It usually begins during ANAPHASE </li></ul>
  27. 32. Observed with place contrast microscopy. The work of Shinya Inoue and Rudolf Oldenbourge.The Mitosis World Website. The work of Mr Paul Maddox . The Mitosis World website . Kangaroo e pithelial kidney cell going through mitotic division. Mitosis and cell plate formation in a flattened endosperm cell of the African bloodlily Haementhus Katherininae.
  28. 33. Cell Turnover - The speed of mitosis <ul><li>Although you may have seen a speeded up video of mitosis in action. One full cycle can vary between a couple of minutes to days. </li></ul><ul><li>For example s kin and epithelial cells have a rapid turnover in the human body in order to replace the ones constantly being worn away. </li></ul><ul><li>C ells which make up organs such as the eye and the brain, need not multiply as often once they reach adult size. </li></ul>Click here for movies
  29. 34. <ul><li>Organs which need to produce new cells continuously have the highest turnover. </li></ul><ul><li>For example :- </li></ul><ul><ul><li>Bone marrow- </li></ul></ul><ul><ul><li>producing replacement </li></ul></ul><ul><ul><li>blood cells </li></ul></ul><ul><ul><li>The testes - producing </li></ul></ul><ul><ul><li>semen </li></ul></ul>
  30. 35. Tumours <ul><li>Abnormalities can sometimes occur in c ells which reproduce at a rapid rate, this in turn may lead to the formation of tumours. </li></ul><ul><li>Tumours of any type should be considered serious. </li></ul><ul><li>Although b enign tumours do n o t usually cause a threat to a persons life , they can cause great inconvenience if not treated. </li></ul>

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