Lesson 5

• What are stem cells?

  Unspecialised cells in the human body
• What does potency of a cell refer to?

  Ability of a stem cell to differentiate
• How does the potency of a stem cell affect its function?

  Greater potency allows for more cell types
• What are the types of stem cell potency?

  • Totipotent
  • Pluripotent
  • Multipotent
  • Unipotent
• What are totipotent stem cells also called?

  Omnipotent
• Where are totipotent stem cells found?

  Zygote, placenta, umbilical cord
• What is the potential of pluripotent stem cells?

  Differentiate into many other cell types
• Where are pluripotent stem cells found?

  Embryo and foetus
• What do multipotent stem cells develop into?

  Limited number of cell types of same tissue
• Where are multipotent stem cells found?

  Bone marrow
• What do diploid cells contain?

  Two copies of every chromosome
• What are homologous chromosomes?

  Chromosomes existing in pairs, one from each parent
• What type of cells are somatic cells?

  Diploid cells in the human body
• What do haploid cells contain?

  One copy of each chromosome
• What are the only haploid cells in humans?

  Gametes
• What are the stages of the cell cycle?

  1. G1 - Growth
  2. S - DNA synthesis
  3. G2 - Growth and preparation for mitosis
  4. M - Mitosis
  5. Cytokinesis
• What occurs during G1 phase of the cell cycle?

  Cell grows and carries out normal functions
• What happens during the S phase of the cell cycle?

  DNA replication takes place
• What occurs during G2 phase of the cell cycle?


  Cell grows and synthesizes ATP and proteins
• What is the mnemonic for nuclear division in mitosis?

  PMAT
• What happens during prophase of mitosis?

  Chromosomes condense and nuclear membrane breaks down
• What occurs during metaphase of mitosis?

  Chromosomes line up along the cell's equator
• What happens during anaphase of mitosis?

  Chromatids are pulled to opposite poles of the cell
• What occurs during telophase of mitosis?

  Separated chromosomes uncoil and nucleus reforms
• What are the stages of meiosis?

  1. Prophase I
  2. Metaphase I
  3. Anaphase I
  4. Telophase I
  5. (Short interphase)
  6. Prophase II
  7. Metaphase II
  8. Anaphase II
  9. Telophase II
• What occurs during prophase I of meiosis?

  Chromosomes condense and crossing over occurs
• What is independent assortment in meiosis?

  Random arrangement of homologous chromosomes at equator
• Compare mitosis and meiosis.

  Mitosis:

  • Occurs in somatic cells
  • Nucleus divides once
  • Produces 2 diploid daughter cells
  • No crossing over
  • Involved in growth and repair

  
  

  Meiosis:

  • Occurs in germ cells
  • Nucleus divides twice
  • Produces 4 haploid daughter cells
  • Crossing over occurs
  • Involved in genetic variation
• How many checkpoints are in the cell cycle?

  Four checkpoints
• What can cause DNA damage in the cell cycle?

  Unreplicated or damaged DNA
• How can cancer be caused by the cell cycle?

  Lack of control leads to uncontrolled division
• What are the two ways genes can become faulty leading to cancer?

  Mutations and inherited faulty genes