Stem cells

• What are stem cells defined as in A-level biology?

  Undifferentiated cells that can divide and specialize
• What is the process by which stem cells become specialized cells called?

  Differentiation
• What are the four types of stem cells?

  • Totipotent
  • Pluripotent
  • Multipotent
  • Unipotent
• What can totipotent stem cells differentiate into?

  Any type of cell in the body
• When are totipotent stem cells available?

  In the very early stages of an embryo
• Where are pluripotent stem cells found?

  In the inner mass of a blastocyst
• What is a potential application of pluripotent stem cells?

  Replacing damaged skin cells
• What issue arises from using pluripotent stem cells in research?

  They can lead to tumor formation
• What is therapeutic cloning?

  Cloning to create stem cells for treatment
• What is the main ethical concern with pluripotent stem cells?

  Destroying embryos during the process
• What do multipotent stem cells differentiate into?

  A limited number of different cells
• Where are multipotent stem cells commonly found?

  In bone marrow
• What do unipotent stem cells differentiate into?

  Only one type of cell
• What is a source of multipotent stem cells besides bone marrow?

  Umbilical cord blood
• What are induced pluripotent stem cells (iPS cells)?

  Adult cells reprogrammed to pluripotent state
• How are iPS cells created?

  By manipulating somatic cells with transcription factors
• What is the benefit of iPS cells over traditional pluripotent stem cells?

  No embryos are destroyed in their creation
• What is the term for returning a cell to a pluripotent state?

  Return to the state of pluripotency
• What do transcription factors do in the context of iPS cells?

  They allow genes to be turned on or off
• What is a key advantage of iPS cells in medical applications?

  They can provide limitless supplies of cells