Mitosis and Apoptosis

• What type of cell division does mitosis produce?

  Identical new cells
• What processes does mitosis support in organisms?

  Growth, cell replacement, and tissue repair
• What is apoptosis often referred to as?

  Natural cell death
• How many mitotic divisions do cells typically undergo before apoptosis?

  Approximately 50 divisions
• What are the processes involved in apoptosis?

  • DNA becomes denser and tightly packed
  • Nuclear envelope breaks down, chromatin condenses
  • Vesicles form containing hydrolytic enzymes
  • Phagocytes engulf and digest the cell
• Why are mitosis and apoptosis important in body plan development?

  They control the development of body form
• What happens to cells produced by mitosis that are no longer needed?

  They are destroyed by apoptosis
• How do fingers and toes develop through apoptosis?

  Cells in between digits are destroyed
• What are the two groups of genes that control mitosis?

  • Proto-oncogenes: stimulate cell division
  • Tumour-suppressor genes: reduce cell division
• What role do tumour-suppressor genes play in damaged cells?

  They can stimulate apoptosis in damaged cells
• What is the purpose of checkpoints during the cell cycle?

  To ensure damaged cells are not produced
• What regulates the progress of the cell cycle?

  • Cyclins: act as regulators
  • Cyclin-dependent kinases (CDKs): act as catalysts
• How do CDKs function in the cell cycle?

  They catalyse phosphorylation of target proteins
• What initiates apoptosis in cells?

  Irreparable genetic damage
• What external factors can affect apoptosis and the cell cycle?

  Cell signalling molecules and harmful agents
• How do cells respond to stressful stimuli?

  By activating survival pathways or initiating apoptosis