STPM Biology Structure of Cell and Organelle (Part 15)

Centriole

Distribution:

• Found in almost all animal cells.
• Not found in plant cells except for lower plant cells such as fungi, algae and bryophytes.

Structure:

• Shape and size: short cylinder; 500nm long and 200nm in diameter.
• A centriole consists of triplets of microtubules in a ‘9+0’ arrangement.
• Neighboring microtubule triplets are connected by fibrils.

Structure of centrioles

Functions:

• Initiates cell division (mitosis and meiosis). cell division begins when centrioles move towards opposite poles.
• Produces spindle during mitosis and meiosis. Spindles are microtubules.
• Involved in the formation of cilia and flagella.