mitosis

• Mitosis and Cytokinesis


  The process of cell division in eukaryotic cells

  
• Cell Cycle


  A repeated pattern of growth and division that occurs in eukaryotic cells
• Stages of Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  
• Cell Cycle


  • Consists of two phases: Interphase and Mitotic division (cell division)

  
• Interphase


  The majority of the cell cycle where the cell grows
• Interphase


  • By the end, the cell has two full sets of DNA (chromosomes) and is large enough to begin division
• Cell Cycle Checkpoints


  • Gap 1 (G1): cell growth and normal functions
  • Gap 2 (G2): additional growth (chromatids become replicated chromosomes)
  • M division: includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)

  
• Mitosis only occurs if the cell is large enough and the DNA is undamaged

  
• Sister Chromatids


  Two identical copies of a chromosome held together at the centromere
• How DNA condenses into a chromosome

  1. DNA wraps around proteins (histones) that condense it

  2. In a typical human cell, there is about 6.5 feet of DNA!
• Chromosomes


  • DNA plus proteins is called chromatin
  • One half of a duplicated chromosome is a chromatid
  • Sister chromatids are held together at the centromere
  • Telomeres protect DNA and do not include genes
• Phases of Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  
• Prophase


  • Chromosomes condense and are more visible
  • Nuclear membrane disappears
  • Centrioles separate and move to opposite poles
  • Spindle fibers form and radiate toward the center
• Metaphase


  • Chromosomes line up across the middle of the cell
  • Spindle fibers connect the centromere of each sister chromatid to the poles
• Anaphase


  • Centromeres split
  • Sister chromatids separate becoming individual chromosomes
  • Separated chromatids move to opposite poles
• Telophase


  • Chromosomes uncoil
  • Nuclear envelope forms around the chromosomes at each pole
  • Spindle fibers break down
  • Cytokinesis begins
• Cytokinesis


  The division of the cytoplasm into two individual cells
• Cytokinesis in Animal Cells

  • Cell membrane forms a cleavage furrow that pinches the cell into two nearly equal parts
• Cytokinesis in Plant Cells

  • A cell plate forms
• Diploid


  Organisms that receive one set of chromosomes from each parent, resulting in two sets of chromosomes
• Haploid


  Cells that have one set of chromosomes, designated as "n"
• Somatic Cells


  Body cells or any non-sex cells that contain two sets of chromosomes, designated as "2n"
• Homologous Chromosomes


  Two chromosomes that are the same, one inherited from each parent