Cell cytoskeleton

Functions of the cytoskeleton

Establishes cell shape, provide mechanical strength, locomotion, chromosome separation in mitosis and meiosis, movement of organelles within a cell

Composition of the cell cytoskeleton

Microtubules, microfilaments and intermediate fibres

Microtubules

25nm in diameter. Globular tubulin proteins polymerise to form tubes. Involved in transport of organelles. Make up the spindle fibres during cell division. 

Microfillaments

7nm in diameter. Contractile fibres formed from the protein actin. Responsible for cell movement and cell contraction during cytokinesis. 

Intermediate fibres

8-10nm in diameter. Give mechanical strength to cells and help maintain their integrity.

Undulipodia and cilia

Hair like extensions that stick out from the surface of cells. Made of 9 pairs of microtubules in a circle w/ two more in the middle (9+2 arrangement)

Function of undulipodia and cilia

Move liquid past the surface of the cell. For single cells this enables them to swim. For anchored cells this moves liquid over the surface of the cell. 

Flagella

Only present in bacterial cells. Made of a spiral of flagellin protein attached by a hook to a protein disc than can rotate. 

Advantage of being a eukaryote: division of labour

Organelles allow for division of labour. Each organelle is specialised to carry out a specific role.