Cell cycle + mitosis

• State the stages of the cell cycle

  1. DNA and chromosomes replicate and the number of sub cellular structures increase

  2. Chromosomes line up in the middle of the cell and are pulled to either end

  3. Cytoplasm and cell membrane divide. Two new daughter cells are formed
• Why is mitosis important?

  • Used for growth and repair plus asexual reproduction
• What is a chromosome?

  • DNA structures found in the nucleus
• How many chromosomes are in human cells?

  • 46 or 23 pairs
  • gametes have 23 in total
• What is a stem cell?

  • Undifferentiated cell that can divide to produce many specialised cell of the same type
• What are the types of stem cells?

  • Embryonic
  • Adult
  • Meristems in plants
• What are the functions of Embryonic stem cells?

  • Can differentiate into any type of cell
  • Can be used to treat diseases such as; diabetes, Alzheimer's and paralysis by replacing faulty cells
• What is the function of adult bone marrow stem cells?

  • Can form many types of cells like blood cells
  • For repair and replacing worn out cells
  • Can treat diseases like leukaemia
• What is the function of meristem plant cells?

  • Growth & repair
  • Regeneration
  • Cloning other plants
• What is therapeutic cloning?

  • Producing an embryo with the same genes as patient
• What are the uses of embryo's produced in therapeutic cloning

  • Harvested to make embryonic stem cells
  • Grown into any cells patients need like tissues/organs
  • An advantage is less chance of rejection as they have same genetic make up as patient
• What are some benefits of using stem cells?

  • Can be used to replace diseased or damaged body parts
  • It uses unwanted embryos from fertility clinics that would otherwise have been discarded
• What are some disadvantages of using stem cells?

  • Ethical concerns
  • risk of tumour formation
  • rejection by the immune system.
  • risk of virus transfer
  • Removal of stem cells results in destruction of embryos
  • Time and money could be spent in other parts of medicine
• Advantages of using embryonic stem cells in comparison to adult stem cells

  • Can differentiate into any type of cell
  • offer better opportunities to study genetic disorders and early human development
• Disadvantages of using embryonic stem cells in comparison to adult stem cells?

  • Ethical concerns as harvesting embryonic stem cells destroys embryo
  • Risk of tumours
  • Risk of rejection
• Advantages of using adult stem cells in comparison to embryonic stem cells

  • Fewer ethical issues as harvesting adult stem cells doesn't harm the donor
  • Lower risk of rejection
  • Already widely used in medicine to treat conditions like leukaemia
• Disadvantage of using adult stem cells compared to embryonic

  • Process of obtaining them is painful
  • They can only differentiate into a limited number of cells
  • They don't divide as quickly or easily as embryonic stem cells