The Role of Stem Cells (Cambridge (CIE) A Level Biology): Revision Note

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)