producing new cells

• step 1 of mitosis:

  In the original parent cell, the chromosomes replicate and double. Forming 2 identical chromatids joined in the centre by a centromere.
• step 2 of mitosis :The nuclear membrane breaks down and the chromosomes shorten and thicken, becoming visible under a microscope
• step 3 of mitosis:

  The chromatids line up along the equator of the cell.
• step 4 of mitosis:

  Spindle fibres attach to the chromatids.
• step 5 of mitosis:

  Spindle fibres shorten pulling the chromatids apart to opposite poles of the cell.
• step 6 mitosis:

  The cytoplasm divides and a nuclear membrane forms.
• step 7 of mitosis:

  2 diploid cells produced, containing the same genetic information as the original parent cell.
• A diploid cell has two matching sets of chromosomes.
• Most cells (the exception being the gametes) in the human body are diploid. They contain 2 sets of 23 chromosomes, giving a total of 46 chromosomes.
• Both sets of chromosomes are replicated during mitosis
• Mitosis maintains the diploid chromosome complement of the new cells, providing the body with new cells that can be used in growth and repair.
• A stem cell in an animal is an unspecialised cell that can divide to self-renew (produce more stem cells) or become specialised. They have the potential to become any cell type in the body.
• Stem cells are used in growth and repair.
• There are 2 types of stem cell:

  • Embryonic stem cells are taken from an embryo at a very early stage.
  • Tissue stem cells are found in the body throughout life
• Cells become specialised to give rise to a variety of cells, each with a particular function.
• A tissue is a group of cells.
• An organ is a group of tissues
• An organ system is a group of organs.
• An organ contains cells specialised for a particular function and groups of organs work together to form systems.
• cells → Tissues → Organs → Organ systems