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Cell division lec

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  • 1. The Cell Cycle & Cell Division
  • 2. The Cell Cycle http://www.nobel.se/medicine/laureates/2001/press.html
  • 3. Cell division is a fundamental process
    • All cells come from pre-existing cells
    • It is necessary to replace worn out cells in multicellular organisms
    • It is required for growth in multicellular organisms
      • An increase in size will require an increase in surface area to volume ration
      • Cell division subdivides the cytoplasm into small units (cells) surrounded by plasma membranes
    • It is necessary for reproduction in unicellular or multicellular organisms
    © 2007 Paul Billiet ODWS
  • 4. Cell division and reproduction
    • It is necessary for reproduction in unicellular or multicellular organisms
    © 2007 Paul Billiet ODWS Microbus © Microscope-Microscope.org
  • 5. Prokaryotes
    • Prokaryotes have no nucleus
    • They have a single circular chromosome
    • Prokaryotes simply divide their cells in two by binary fission
    http://instruct1.cit.cornell.edu/ © 2007 Paul Billiet ODWS
  • 6. Eukaryotes
    • Eukaryotes must divide their nucleus (and other organelles such as mitochondria) in preparation for cell division (mitosis or meiosis)
    • Before the nucleus divides the genetic material replicates (duplicates)
    © 2007 Paul Billiet ODWS
  • 7. Animated Cycle http://www.cellsalive.com/cell_cycle.htm
  • 8. MITOSIS
  • 9. Mitosis The process of cell division which results in the production of two daughter cells from a single parent cell. The daughter cells are identical to one another and to the original parent cell.
  • 10. Chromosomes – rod-like structures, consisting of nucleic acids and protein, located within the nucleus The no.of chromosomes per nucleus is normally constant for all the individuals of a species, e.g. Man has 46, rat 42, garden pea 14 and tomato 24. Every body (somatic ) cell contains the characteristic number of chromosomes but mature germ cells ( gametes ) contain only half the usual number one member of each pair. The gametes are described as haploid in chromsome number and the somatic cell as diploid .
  • 11.  
  • 12. Mitosis can be divided into stages
    • Interphase
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase & Cytokinesis
  • 13. Interphase The cell prepares for division
    • Animal Cell
      • DNA replicated
      • Organelles replicated
      • Cell increases in size
    • Plant Cell
      • DNA replicated
      • Organelles replicated
      • Cell increases in size
  • 14. Interphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  • 15. Prophase The cell prepares for nuclear division
    • Animal Cell
      • Packages DNA into chromosomes
    • Plant cell
      • Packages DNA into chromosomes
  • 16. Prophase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  • 17. Metaphase The cell prepares chromosomes for division
    • Animal Cell
      • Chromosomes line up at the center of the cell
      • Spindle fibers attach from daughter cells to chromosomes at the centromere
    • Plant Cell
      • Chromosomes line up at the center of the cell
      • Spindle fibers attach from daughter cells to chromosomes at the centromere
  • 18. Metaphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  • 19. Anaphase The chromosomes divide
    • Animal Cell
      • Spindle fibers pull chromosomes apart
      • ½ of each chromosome (called chromotid) moves to each daughter cell
    • Plant Cell
      • Spindle fibers pull chromosomes apart
      • ½ of each chromosome (called chromotid) moves to each daughter cell
  • 20. Anaphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  • 21. Telophase The cytoplasm divides
    • Animal Cell
      • DNA spreads out
      • 2 nuclei form
      • Cell wall pinches in to form the 2 new daughter cells
    • Plant Cell
      • DNA spreads out
      • 2 nuclei form
      • New cell wall forms between to nuclei to form the 2 new daughter cells
  • 22. Telophase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  • 23. Animal Mitosis -- Review Interphase                                                               Prophase                                                               Metaphase                                                               Anaphase                                                               Telophase                                                               Interphase                                                              
  • 24. Plant Mitosis -- Review Interphase                                                               Prophase                                                               Metaphase                                                               Anaphase                                                               Telophase                                                               Interphase                                                              
  • 25.  
  • 26. MEIOSIS
  • 27. Meiosis Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced. One parent cell produces four daughter cells. Daughter cells have half the number of chromosomes found in the original parent cell
  • 28. Meiosis During meiosis, DNA replicates once , but the nucleus divides twice .
  • 29. Meiosis Four stages can be described for each division of the nucleus.
  • 30. Meiosis I First division of meiosis
  • 31. First Division of Meiosis
    • Prophase 1: Each chromosome duplicates and remains closely associated. These are called sister chromatids.
    • Metaphase 1 : Chromosomes align at the center of the cell.
    • Anaphase 1 : Chromosome pairs separate with sister chromatids remaining together.
    • Telophase 1 : Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair.
  • 32. Prophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 33. Prophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 34. Metaphase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 35. Telophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 36. Meiosis Second Division of Meiosis
  • 37. Second Division of Meiosis
    • Prophase 2 : DNA does not replicate.
    • Metaphase 2 : Chromosomes line up at the center of the cell
    • Anaphase 2 : Centromeres divide and sister chromatids move separately to each pole.
    • Telophase 2 : Cell division is complete.
    • Four haploid daughter cells are formed .
  • 38. Prophase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 39. Metaphase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 40. Telophase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
  • 41. Meiosis http://www.biosci.uga.edu/almanac/bio_103/notes/apr_3.html .
  • 42.  
  • 43.  
  • 44. Meiosis Animation http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/movie/meiosis.htm
  • 45. Differences in Mitosis & Meiosis
    • Mitosis
      • Asexual
      • Cell divides once
      • Two daughter cells
      • Genetic information is identical
    • Meiosis
      • Sexual
      • Cell divides twice
      • Four haploid daughter cells
      • Genetic information is different
  • 46. Comparison Animations http://www.pbs.org/wgbh/nova/baby/divi_flash.html http://www.usoe.k12.ut.us/curr/science/sciber00/7th/genetics/sciber/animatin.htm