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Biology AS CIE

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  1. 1-cell-structure
    10 主题
  2. 2-biological-molecules
    19 主题
  3. 3-enzymes
    13 主题
  4. 4-cell-membranes-and-transport
    16 主题
  5. 5-the-mitotic-cell-cycle
    8 主题
  6. 6-nucleic-acids-and-protein-synthesis
    9 主题
  7. 7-transport-in-plants
    11 主题
  8. 8-transport-in-mammals
    16 主题
  9. 9-gas-exchange
    6 主题
  10. 10-infectious-diseases
    6 主题
  11. 11-immunity
    10 主题
课 5, 主题 4
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5-1-replication-and-division-of-nuclei-and-cells AS the-role-of-stem-cells

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Exam code:9700

The significance of stem cells

  • A stem cell is a cell that can divide (by mitosis) an unlimited number of times

  • Each new cell (produced when a stem cell divides) has the potential to:

    • Remain a stem cell

    • Develop into a specialised cell such as a blood cell or a muscle cell

      • Developing into a specialised cell occurs through a process known as differentiation

  • This ability of stem cells to differentiate into more specialised cell types is known as potency

Multipotent adult stem cells

  • As tissues, organs, and organ systems develop, cells become more and more specialised

  • Having differentiated and specialised to fulfil particular roles, most adult cells gradually lose the ability to divide until, eventually, they are no longer able to divide

  • However, small numbers of stem cells (known as adult stem cells) remain to produce new cells for the essential processes of growth, cell replacement and tissue repair

    • They are known as multipotent adult stem cells

  • Although these multipotent adult stem cells can divide (by mitosis) an unlimited number of times, they are only able to produce a limited range of cell types

    • For example, the stem cells found in bone marrow are multipotent adult stem cells—they can only differentiate into blood cells (red blood cells, monocytes, neutrophils, and lymphocytes)

  • In adults, stem cells can be found throughout the body (e.g. in the bone marrow, skin, gut, heart, and brain)

  • Research is being carried out on stem cell therapy, which is the introduction of adult stem cells into damaged tissue to treat diseases (e.g. leukaemia) and injuries (e.g. skin burns)

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