Centrioles, cilia, flagella (OCR)

• Centrioles


  Pair of structures made of microtubules found in many eukaryotic cells
• Centrioles


  • Found in animal cells, certain simple plants and algae, but not in flowering plants or most fungi
  • Lie at right angles to each other
  • Often found near the nucleus
  • Together form the centrosome
• Functions of centrioles


  1. Role in assembly of spindle fibers during mitosis and meiosis

  2. Role in formation of cilia and flagella
• Plant cells form spindle fibers during cell division without containing centrioles
• Cilia


  Hair-like organelles that extend from the surface of certain cells
• What does Cilia do

  • Beat in waves to waft dust particles along the trachea and push them out of the lungs
  • Found in Fallopian tubes to waft egg cells towards the uterus
  • Some cilia play a role in sensing chemicals around the cell
• Flagella


  Whip-like organelles found on the surface of certain cells, such as sperm cells, to move the cell
• Role of Flagella


  • Longer than cilia
  • Eukaryotic cells usually have only one flagellum
• Cilia and flagella have a common structure of nine pairs of microtubules arranged in a circle with another pair in the center (nine plus two structure)
• The movement of cilia and flagella is powered by the pairs of microtubules moving relative to each other, using energy from ATP
• The formation of cilia and flagella depends on a complex of proteins, with a centriole being a key part of this protein complex