Cell division

• What is a stem cell?

  Undifferentiated cell that can differentiate into one or more specialised cell types
• What are adult stem cells?

  Stem cells from adults that can only differentiate into certain specialised cells
• Where are adult stem cells found?

  Bone Marrow
• What are embryonic stem cells?

  Stem cells from embryos that can differentiate into any specialised cells
• Where are embryonic stem cells found?

  Early human embryos (usually from spare embryos from fertility clinics)
• What is therapeutic cloning?

  Patient's cells are used to create an early embryo in clone of themselves - stem cells from the embryo can then be used to treat the patient's medical conditions
• Give one advantage of using therapeutic cloning?

  Stem cells from the embryo are not rejected when transplanted because they have the same genes as the patient
• Give one advantage of using adult stem cells?

  Fewer ethical issues as obtained from adults who can consent to their use
• Give two disadvantages of using adult stem cells?

  Can take a long time for a suitable donor to be found

  Can only differentiate into some specialised cell types, so treat fewer diseases
• Give two advantages of using embryonic stem cells

  Can differentiate into any specialised cell, so can be used to treat many diseases

  Easier to obtain as they are found in spare embryos from fertility clinics
• Give two disadvantages of using embryonic stem cells

  Ethical issues surrounding their use as every embryo is a potential life

  Potential risks involved with treatments, such as transfer of viral infections
• What are plant Meristems?

  Area where rapid cell division occurs in the tip of roots and shoots
• Give two advantages of using plant Meristems to clone plants

  Rare species can be cloned to protect them from extinction

  Plants with special features can be cloned to produce many copies
• Give one disadvantages of using plant Meristems to clone plants

  No genetic variation, so for example, an entire cloned crop could be destroyed by a disease
• What is cell division by mitosis?

  Body cells divide to form two identical daughter cells
• What is the purpose of mitosis?

  Growth and repair of cells, and asexual reproduction
• What happens during the first stage of the cell cycle?

  Cells grow bigger, chromosomes duplicate, number of sub-cellular structures increase
• What happens during mitosis? 


  One set of chromosomes is pulled to each end of the cell and the nucleus divides
• What happens during the third stage of the cell cycle?

  The cytoplasm and cell membrane divide, forming two identical daughter cells