Chromosomes and Mitosis.

• What are chromosomes? 


  coiled up lengths of DNA molecules.
• What do chromosomes carry?


  large numbers of genes.
• What do different Genes carry?


  the development of different characteristics.
• How many pairs of chromosomes do body cells usually carry?


  2.
• Where do the chromosomes come from?


  1 from the organisms mother and 1 from the father.
• How many pairs of chromosomes do human cells carry?


  23 pairs, 46 total.
• Why do multicellular organisms use mitosis?


  To grow or replace cells that have been damaged.
• Stages of Growth & DNA replication.

  1. The DNA is all spread out in king strings
  2. before it divides the cell has to grow and increase the amount of sub cellular structures such as mitochondria and ribosomes.
  3. It then duplicates its DNA so there’s one copy for each new cell. The DNA then copied forms X-Shaped chromosomes. Each ‘arm’ is an exact duplicate of the other.
• Stages of Mitosis

  1. The chromosomes line up at the center of the cell and the fibres pull them apart. The two arms go to opposite ends of the cell.
  2. Membranes form around each new set of chromosomes, these become the new nuclei - the nucleus has divided.
  3. Lastly the Cytoplasm and cell membrane divide.
  4. The cell has now produced two new daughter cells. They’re identical, their DNA is also identical to the Parent cell.