Chromosomes and Mitosis

• Chromosomes


  Coiled up lengths of DNA molecules that contain genetic information
• Most cells in the body have a nucleus that contains chromosomes
• Each chromosome carries a large number of genes that control the development of different characteristics
• Body cells normally have two copies of each chromosome, one from the 'mother' and one from the 'father'
• Humans have 23 pairs of chromosomes
• Cell cycle


  A series of stages that body cells in multicellular organisms go through to divide and produce new cells for growth, development and repair
• Mitosis


  The stage of the cell cycle when the cell divides
• Mitosis


  1. Chromosomes line up at the centre of the cell

  2. Cell fibres pull the chromosomes apart

  3. Membranes form around each set of chromosomes to become the nuclei of the two new cells

  4. Cytoplasm and cell membrane divide
• Mitosis produces two identical daughter cells with the same DNA as the parent cell
• Growth and DNA replication stage of cell cycle


  • DNA is duplicated and forms X-shaped chromosomes with two identical 'arms'