Chromosomes and mitosis

• The nucleus contains your genetic materials in the form of chromosomes.
• Chromosomes are coiled up lengths of DNA molecules.
• Each chromosome carries a large number of genes.
• Body cells normally have two copies of each chromosome-one from the organisms mother and one from its father.
• The cell cycle makes new cells for growth, development and repair.
• Body cells in multicellular organisms divide to produce new cells as part of a series of stages called the cell cycle.
• The stage of the cell cycle when the cell divides is called mitosis.
• Multicellular organisms use mitosis to grow or replace cells that have been damaged.
• The end of the cell cycle results in two new cells identical to the original cell, with the same number of chromosomes.
• In a cell that’s not dividing, the DNA is all spread out in long strings.
• Before a cell divides, it has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
• The cell duplicates its DNA- so there’s one copy for each new cell.
• The DNA is copied and forms x-shaped chromosomes; each ‘arm’ of the chromosome is an exact duplicate of the other.
• After the contents and DNA have been copied the chromosomes line up at the centre of the cell and cell fibres pull them apart.
• The two arms of each chromosome go to the opposite ends of the cell.
• Membranes form around each of the sets of chromosomes.
• These become the nuclei of the two new cells- the nucleus has divided.
• The cytoplasm and cell membrane divide.
• The cell has now produced two new daughter cells.
• The daughter cells contain exactly the same DNA- they’re identical.
• Their DNA is also identical to the parent cell.