OCR AS Biology

Revision Notes

2.1.8 The Cytoskeleton

The Cytoskeleton

  • Within the cytoplasm of cells, there is an extensive network of protein fibres
    • This is known as the cytoskeleton
  • The cytoskeleton is made up of two main types of protein fibres: microfilaments and microtubules
    • Microfilaments are solid strands that are mostly made of the protein actin. These fibres can cause some cell movement and the movement of some organelles within cells by moving against each other
    • Microtubules are tubular (hollow) strands that are mostly made of the protein tubulin. Organelles and other cell contents are moved along these fibres using ATP to drive this movement
  • Intermediate filaments (a third type of fibre) are also found within the cytoskeleton

The importance of the cytoskeleton

  • The cytoskeleton is important as it has several different functions, including:
  • Strengthening and support:
    • The cytoskeleton provides the cell with mechanical strength, forming a kind of ‘scaffolding‘ that helps to maintain the shape of the cell
    • It also supports the organelles, keeping them in position
  • Intracellular (within cell) movement:
    • The cytoskeleton aids transport within cells by forming ‘tracks’ along which organelles can move
    • Examples of this include the movement of vesicles and the movement of chromosomes to opposite ends of a cell during cell division
  • Cellular movement:
    • The cytoskeleton enables cell movement via cilia and flagella
    • These structures are both hair-like extensions that protrude from the cell surface and contain microtubules that are responsible for moving them

Cytoskeleton, downloadable AS & A Level Biology revision notes

The cytoskeleton provides mechanical strength to cells, aids transport within cells and enables cell movement

Exam Tip

For the exam, you only need to be aware of the two main types of protein fibres within the cytoskeleton: microfilaments and microtubules. The third type (intermediate filaments) are shown here to give extra detail on the composition of the cytoskeleton.

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