mitosis and cell cycle 1.2.2

• there are 2 types of cell division: mitosis and meiosis
• mitosis is the most popular cell division (99.9% of cells)
• meiosis is only when we create a child
• mitosisis used for 3 reasons: growth of new cells, repair and replacement of worn out cells and asexual reproduction in plants and yeast
• mitosis is used in plants, in special areas called meristems (root or shoot tip)
• mitosis occurs throughout the life of an organism
• stage 1 of mitosis is the longest stage where the cells grow bigger and increase mass, their genes replicate themselves to make two chromosomes and there is an increase in number of all organelles
• stage 2 of mitosis is where the chromosomes pair up on the equator of a cell and one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides
• stage 3 of mitosis is where the cytoplasm and cell membranes also divide to form two genetically identical daughter cells
• 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 and develop or replace cells that have been damaged
• the end of the cell cycle results in 2 new cells identical to the original cell, with the same number of chromosomes
• stage 1:

  • before a cell can divide, it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria
  • the cell then replicates the dna to form 2 copies of each chromosome
• stage 2:

  • the chromosomes pair up at the equator of the cell
  • cell fibres pull them apart and the 2 arms of each chromosome go to opposite ends of the cell
  • membranes form around each of the sets of chromosomes, these become the nuclei of the 2 new cells - the nucleus has divided
• stage 3:

  • the cytoplasm and cell membrane divide
  • this forms 2 new genetically identical daughter cells