Mitosis and Meiosis

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Mitosis and Meiosis

  1. 1. Talk to your neighbors about: -How does your body repair itself? -How does your body grow? -Do you think you have the same cells you were born with?
  2. 2. CELL REPRODUCTIONCELL REPRODUCTION CELL CYCLE, BINARY FISSION, MITOSIS & MEIOSISCELL CYCLE, BINARY FISSION, MITOSIS & MEIOSIS
  3. 3. 20 µm100 µm 200 µm (a) Reproduction. An amoeba, a single-celled eukaryote, is dividing into two cells. Each new cell will be an individual organism (LM). (b) Growth and development. This micrograph shows a sand dollar embryo shortly after the fertilized egg divided, forming two cells (LM). (c) Tissue renewal. These dividing bone marrow cells (arrow) will give rise to new blood cells (LM).
  4. 4.  Genetic information – genome  Packaged into chromosomes 50 µm Figure 12.3
  5. 5.  An average eukaryotic cell has about 1,000 times more DNA then an average prokaryotic cell.  The DNA in a eukaryotic cell is organized into several linear chromosomes, whose organization is much more complex than the single, circular DNA molecule in a prokaryotic cell
  6. 6.  All eukaryotic cells store genetic information in chromosomes.  Most eukaryotes have between 10 and 50 chromosomes in their body cells.  Human cells have 46 chromosomes.  23 nearly-identical pairs
  7. 7. Press Pause, Think, & Share 1) What are the functions of cell division? (Hint there are three main functions) 2) Which structures in the nucleus stores genetic information? 3) How many chromosomes does a human have in their normal body cells?
  8. 8. 1) What are the functions of cell division? (Hint there are three main functions)  Reproduction in some organisms (unicellular)  Growth  Repair 1) Which structures in the nucleus stores genetic information?  Chromosomes 1) How many chromosomes does a human have in their normal body cells?  46 (23 pairs)
  9. 9.  Eukaryotic cells divide by mitosis  Each new cell receives one copy of every chromosome that was present in the original cell.  Produces 2 new nuclei that are both genetically identical to the original cell. DNA duplication during interphase Mitosis Diploid Cell
  10. 10. BINARY FISSIONBINARY FISSION  Most cells reproduceMost cells reproduce through some sort ofthrough some sort of CellCell DivisionDivision  Prokaryotic cells divideProkaryotic cells divide through a simple form ofthrough a simple form of division calleddivision called BinaryBinary FissionFission  3 step process3 step process  Single “naked” strandSingle “naked” strand splits and forms asplits and forms a duplicate of itself.duplicate of itself.  The two copies move toThe two copies move to opposite sides of the cellopposite sides of the cell  Cell “pinches” into two newCell “pinches” into two new and identical cells calledand identical cells called “daughter cells”daughter cells”. (Cell wall”. (Cell wall then forms if applicable)then forms if applicable)
  11. 11.  The process by which eukaryotic cells reproduce themselves, resulting in daughter cells that contain the same amount of genetic material as the parent cell.  Occur in body cells (somatic cells)
  12. 12. How do mitosis and binary fission compare???
  13. 13. Animated Mitosis Cycle http://www.cellsalive.com/mitosis.htm • Prophase • Metaphase • Anaphase • Telophase
  14. 14. • Nuclear envelope disappears • Centrioles appear and begin to move to opposite end of the cell. • Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers
  15. 15. Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Spindle fibers Centrioles
  16. 16. • Chromatids (or pairs of chromosomes) attach to the spindle fibers. • Line up in the middle of the cell Centrioles Spindle fibers
  17. 17. Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  18. 18. • Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers
  19. 19. Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  20. 20. • Two new nuclei form. • Chromosomes appear as chromatin (threads rather than rods). • Mitosis ends. NucleiNuclei Chromatin
  21. 21. Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
  22. 22. 23
  23. 23. Press Pause, Think, & Share 1) What are the phases of mitosis (hint: there are 4) 2) Describe the major even that happens in each phase.
  24. 24. 1) What are the phases of mitosis? (Hint: there are four)  Prophase  Metaphase  Anaphase  Telophase 1) Describe the major even that happens in each step.  Prophase= spindle fibers form, nuclear envelope disappears  Metaphase= chromatids line up at center of cell  Anaphase= chromatids are pulled to opposite ends of the cell  Telophase= 2 new nuclear envelopes appear, mitosis ends
  25. 25.  Use the guided notes to create a mitosis foldable.  Once you are finished share your paper with a partner.  Make any necessary changes.
  26. 26. MEIOSISMEIOSIS  Similar in many ways to mitosisSimilar in many ways to mitosis  Several differencesSeveral differences  Involves 2 cell divisionsInvolves 2 cell divisions  Results in 4 cells with 1/2 the normal geneticResults in 4 cells with 1/2 the normal genetic informationinformation
  27. 27. VOCABULARYVOCABULARY  Diploid (2N)Diploid (2N) – Normal amount- Normal amount of genetic material (somaticof genetic material (somatic cells)cells)  Haploid (N)Haploid (N) – 1/2 the genetic- 1/2 the genetic material. (gametes)material. (gametes)  Meiosis results in the formationMeiosis results in the formation of haploid cells.of haploid cells.  In Humans, these are theIn Humans, these are the OvaOva (egg) and(egg) and spermsperm..  Ova are produced in theOva are produced in the ovariesovaries in femalesin females  Process is calledProcess is called ooogenesisogenesis  Sperm are produced in theSperm are produced in the testestestes of males.of males.  Process is calledProcess is called spermatogenesisspermatogenesis
  28. 28.  Meiosis occurs in 2 phases; Meiosis I, & Meiosis II.  Meiosis I.  Prior to division, amount of DNA doubles
  29. 29. CROSSING OVERCROSSING OVER  During prophase 1During prophase 1 homologoushomologous chromosomes comechromosomes come together.together.  Areas of homologousAreas of homologous chromosomes connectchromosomes connect at areas calledat areas called chiasmatachiasmata
  30. 30. CROSSING OVER CONTD.CROSSING OVER CONTD.  Crossing OverCrossing Over of genesof genes occurs nowoccurs now  Segments of homologousSegments of homologous chromosomes break andchromosomes break and reform at similar locations.reform at similar locations.  Results in new geneticResults in new genetic combinations of offspring.combinations of offspring.  This is the mainThis is the main advantage of sexualadvantage of sexual reproductionreproduction
  31. 31.  What is the difference between haploid and diploid?  Where are ova and sperm made?  How many phases of meiosis occur?  What is crossing over and when does that occur?
  32. 32.  What is the difference between haploid and diploid?  Haploid (n) contains half the number of chromosomes  Diploid (2n) contains two sets of chromosomes  Where are ova and sperm made?  Testes and ovaries  How many phases of meiosis occur?  2 divisions  What is crossing over and when does that occur?  Leads to genetic diversity, Prophase I
  33. 33.  Does this look familiar?  Can you explain what is happening?
  34. 34.  DNA does not double  Chromosomes randomly line-up along metaphase plate like regular mitosis.  During anaphase 2, CENTROMERES BREAK and each chromosome is pulled to opposite sides of the cell.  Nuclei reform and cytokenesis usually occurs (although it is often unequal).
  35. 35. OVERVIEW OF MEIOSISOVERVIEW OF MEIOSIS
  36. 36. COMPARISON OF MITOSIS & MEIOSISCOMPARISON OF MITOSIS & MEIOSIS
  37. 37. Press Pause, Think, & Share 1) When does crossing over occur? What benefit does it create over asexual reproduction? 2) How many times does the nucleus divide in Meiosis? 3) How many cells are produced from Meiosis?
  38. 38. 1) When does crossing over occur? What benefit does it create over asexual reproduction? – Prophase I – Due to crossing over species have genetic diversity 1) How many times does the nucleus divide? – Twice, during Meiosis and I and again in Meiosis II 1) How many cells are produced from Meiosis? – 4 different, haploid, gamete cells
  39. 39. Time to Write
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