Differentiation and stem cells

• What does differentiation mean?

  When a cell gets different sub-cellular structures to enable it to carry out a certain function. (specialised for its function)
• What are stem cells?

  Undifferentiated cells.
• What can stem cells from embryo cells be used for?

  Can be cloned and made to differentiate into most different types of human cells.
• What can the meristem be used for in a plant?

  Can differentiate into any type of plant cell throughout the life of the plant.
• What are the differences between differentiation in plant cells and animal cells?

  1. Most animal cells only differentiate once at an early stage of life
  2. Most plant cells have the ability to differentiate more than once throughout their life.
• Where is the meristem in a plant?

  tips of the roots.
• What conditions can stem cell treatment help?

  Paralysis and diabetes.
• What happens in therapeutic cloning?

  Creation of genetically identically stem cells as the patient.
• Why is therapeutic cloning beneficial?

  The cells produced have the same genetic makeup as the patient so they are not rejected
• What two things can stem cells do?

  1. Can divide by mitosis to produce more cells
  2. Can differentiate into different types of specialised cells.
• What are the two main type of stem cell?

  Embryonic stem cells and adult stem cells.
• What are the features of adult stem cells?

  1. Found in an early embryo.
  2. Can differentiate into any type of specialised cell.
• What are the features of adult stem cells?

  1. Found in the bone marrow
  2. Can only differentiate into different types of blood cells.
• What condition can adult stem cells treat and why?

  Sickle cell anaemia because the condition is caused by misshapen blood cells and adult stem cells can differentiate into different blood cells.
• What is the process of using embryonic stem cells to treat a condition involving faulty cells?

  1. Extract embryonic stem cells from early embryos.
  2. Grow them in a laboratory
  3. Stimulate them to grow into the specific type of specialised cell is needed
  4. Then use them to replace the faulty cell (cell replacement)
• What are the disadvantages of embryonic stem cell treatment?

  • Limited supply - from embryos
  • Rejection - because the patient and the embryo have different genomes so the immune system may destroy the new stem cells identifying them as foreign.
• Why won't adult stem cells cause rejection?

  Because they can be taken directly from the patient so the immune system will not identify the new stem cells as foreign because it is the patient's own cells.
• What are the benefits of using the stem cells from the meristem of plants?

  • Rare species can be cloned to protect from extinction.
  • Crop plants with special features (e.g disease resistance) can be cloned to produce large numbers of identical plants for farmers.
• What are the two risks of using stem cells in medicine and why?

  • Tumour development - because the stem cells rapidly divide there is a chance they'll become out of control once they've been transplanted and develop into a tumour or cancer.
  • Virus transmission - if the stem cell was infected with a virus either from the person donating or from the lab it can then infect the patient causing more problems.
• What are the ethical issues associated with embryonic stem cell research?

  That people see the embryos as having a potential for human life so they object to them being used in the research.
• What are the solutions to the negative ethical opinions on stem cell research?

  • Usually the embryos are unwanted ones from fertility clinics which otherwise would've been destroyed
  • If its legal, governments have laws and rules scientists have to follow (tightly controlled) (e.g in the UK)