chromosomes and 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


  Usually spread out in long strings, condenses into chromosomes when cell prepares for division
• Chromosomes


  • Packets of DNA containing a large number of genes that control development of different characteristics
  • Eukaryotic cells have two copies of each chromosome, one from each parent
• Humans have 23 pairs of chromosomes, 46 in total
• Chromosome duplication


  Duplicate stays attached to original chromosome, forming an X shape
• Cell division


  1. Chromosomes line up at cell center

  2. Fibers from either side attach to chromosome halves and pull them to opposite sides

  3. Cell membrane and cytoplasm pull apart, forming two daughter cells
• Resulting daughter cells have the same DNA and are identical to each other and the parent cell
• Daughter cells can then undergo the cell cycle again