The Cell Cycle

• Why are new cells needed for an organism?

  To grow and replace damaged tissue
• What do new cells need to do the same job?

  They need the same genetic information
• What does each cell contain that is crucial for genetic information?

  A nucleus containing chromosomes
• What do chromosomes carry?

  Genes that contain instructions for cells
• What is a gene?

  A small packet of information controlling characteristics
• How many chromosomes do body cells have?

  46 chromosomes arranged in 23 pairs
• What do sex cells (gametes) contain?

  One chromosome from each pair
• What are the stages of the cell cycle?

  1. Interphase: cell growth and DNA replication
  2. Mitosis: division of the nucleus
  3. Cytokinesis: division of cytoplasm and membranes
• What happens during interphase?

  Cells grow, replicate DNA, and increase structures
• What occurs during mitosis?

  Chromosomes are pulled to each end of the cell
• What is the result of cytokinesis?

  Two identical daughter cells are formed
• How many cells are estimated to be in an adult human?

  37.2 trillion cells
• Why are not all cells the same in the body?

  Cells differentiate as they grow and develop
• What are stem cells?

  Unspecialised cells that can become any type
• When do animal cells typically differentiate?

  Early in life, before birth
• What can most specialised cells do?

  Divide by mitosis to produce the same type
• What happens to blood cells in terms of division?

  They cannot divide and need adult stem cells
• Where are adult stem cells generally found?

  In bone marrow
• How do plant cells differ in differentiation compared to animal cells?

  Plant cells can differentiate throughout their lives
• What are meristems?

  Active regions where undifferentiated cells form
• What happens to plant cells at growing points?

  They elongate and grow before differentiation
• What is cloning in plants?

  Producing identical offspring from one plant
• Why is it difficult to clone humans?

  Animal cells differentiate permanently early on
• What forms when an egg and sperm cell fuse?

  A zygote
• What are embryonic stem cells?

  Cells that differentiate to form specialized cells
• What breakthrough occurred in 1998 regarding stem cells?

  Scientists cultured human embryonic stem cells
• What have scientists grown from embryonic stem cells?

  Nerve cells to help stop paralysis
• What was a positive outcome of stem cell transplants in 2014?

  Improvement in eyesight for blind patients
• How can stem cells in plants be used economically?

  To make clones of mature plant cells quickly
• What ethical concerns exist regarding embryonic stem cells?

  Embryos cannot give permission for use
• What is a concern regarding the rapid division of embryonic stem cells?

  They might cause cancer
• What is a risk associated with adult stem cells?

  They might be infected with viruses
• What is therapeutic cloning?

  Using adult cells to create matched embryonic cells
• What potential benefit does therapeutic cloning offer?

  Development of organs that won't be rejected
• What have scientists discovered in tubes connecting the liver and pancreas?

  Stem cells that can produce insulin cells
• What are current treatments using stem cells?

  • Spinal cord injuries
  • Diabetes management
  • Heart recovery after attacks
  • Restoring eyesight in the blind
  • Repairing damaged bone and cartilage