STPM Biology Structure of Cell and Organelle (Part 13)

Microtubules

Distribution:

• Found all over the cytoplasm of cells.
• For examples: cilia, flagella and centrioles.

Structure:

• Microtubules are tiny tubules composed of tubulin protein.
• The length of the microtubule varies. Its diameter is about 25nm; the diameter of the lumen is about 15nm.
• Microtubules can break and reassemble.

  

  Animal cell micrograph

Functions:

• Involved in cell division. Spindles are microtubules attached to chromosome during cell division.
• Microtubules in cytoplasm are vital in intracellular transportation. These microtubules contracts and relaxes continuously to move vesicles and organelles.
• Microtubules are cross-linked with microfilaments to form the cytoskeleton. This cytoskeleton provides mechanical support for the cell; it also determines the shape of the cell.
• Microtubules are main components of cilia and flagella. This shows that microtubule plays a part in movement of organisms or cells with cilia or flagella.
• Involved in formation of plant cell walls.