1.2

• What are chromosomes made up of?

  Chromosomes consist of DNA molecules combined with proteins.
• What is the function of genes within chromosomes?

  Genes provide the instructions for protein synthesis.
• How many chromosomes are found in the nucleus of human body cells?

  46
• How many chromosomes are found in the nucleus of gametes?

  23
• How are chromosomes arranged in the nucleus of a body cell?

  Chromosomes are arranged in pairs, forming 23 pairs.
• What are the three main stages of the cell cycle?

  1. Replication of DNA and synthesis of organelles
  2. Mitosis
  3. Division of cell
• Why is mitosis important?

  Mitosis produces identical cells with the same genetic information.
• What additional role does mitosis serve besides producing identical cells?

  Mitosis produces additional cells for growth and repair.
• Describe the first stage of the cell cycle.

  It is the longest stage where cells grow, replicate DNA, and synthesize organelles.
• Describe the second stage of the cell cycle.

  Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.
• Describe the third stage of the cell cycle.

  The cytoplasm and cell membrane divide, producing two identical daughter cells.
• What is a stem cell?

  A stem cell is an unspecialized cell capable of differentiating into other cell types and self-renewal.
• What is the function of stem cells in embryos?

  Embryonic stem cells can replicate and differentiate into many other types of cells.
• How do embryonic stem cells potentially help medical conditions?

  They may treat conditions such as paralysis and diabetes by replacing damaged cells.
• What is the function of stem cells in adult bone marrow?

  Adult stem cells can differentiate into several cell types to replace dead or damaged tissues.
• What is the function of stem cells in plant meristems?

  Meristem stem cells can differentiate into any type of plant cell throughout their lifespan.
• What is therapeutic cloning?

  Therapeutic cloning is a method where an embryo is produced with the same genetic makeup as the patient.
• Why are stem cells from therapeutic cloning not rejected by the patient’s immune system?

  Because the stem cells originate from the embryo with the same genetic makeup as the patient.
• What are the advantages of cloning plants using meristem stem cells?

  • Prevents rare plants from becoming extinct
  • Produces large numbers of plants with favorable characteristics
  • Produces identical plants for research
• What are some issues associated with the use of embryonic stem cells?

  Many embryonic stem cells are sourced from aborted embryos, raising ethical concerns.
• What is a challenge in developing stem cell therapies?

  Development is slow, expensive, and difficult.
• What risk is associated with adult stem cells infected with viruses?

  They could transfer infections to patients.
• What could happen if donor stem cells do not have a similar genetic makeup to the patient?

  An immune response could be triggered.