microtubules

• • Straight cylindrical structures made of protein called tubulin
  • Each microtubule is about 18-30m in diameter
  • Make up centrioles, cilia and undulipodia
• • Provide shape and support to cells
  • Help substances and organelles to move through the cytoplasm (form a track whereby motor proteins called dynein and kinesin drag and walk organelles along track)
  • Form spindle fibres before cell divides