Mitosis

• Multicellular eukaryotic organisms require a continuous supply of new cells for growth, development and repair
• The process through which these cells are generated is known as the cell cycle
• Cell cycle

  1. Growth

  2. DNA replication

  3. Mitosis and division (cytokinesis)
• DNA

  When a cell is not dividing, it is spread out in long strings. When preparing for division, it condenses into chromosomes
• Chromosomes

  • Packets of DNA
  • Each chromosome contains a large number of genes that control the development of different characteristics
• Eukaryotic cells have two copies of each chromosome, one from the mother and one from the father
• Humans have 23 pairs of chromosomes, for a total of 46 chromosomes
• Chromosome duplication


  The right half of each chromosome is a duplicate of the left half
• Cell division

  1. Chromosomes line up along the center of the cell

  2. Fibers from either side of the cell attach to the respective half of each chromosome

  3. Chromosomes are pulled to opposite sides of the cell, breaking them in half

  4. Cell membrane and cytoplasm pull apart, forming two daughter cells
• The resulting daughter cells have the same DNA as the parent cell
• The daughter cells can then undergo the cell cycle all over again