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Cell Structure and Cell Organelles

The Cytoskeleton

The cytoskeleton consists of a network of protein fibers that provide a cell with form and stability while allowing movement and shape changes. The fibers are differentiated by thickness into the roughly 8 nm thick microfilaments, made of the globular protein actin and thus also often called actin filaments, intermediate filaments, which are made of proteins like creatine, and the microtubules, which are about 25 nm thick and made of globular tubulin formed into hollow cylinders. The cell-division apparatus (spindle apparatus), the centrosome that contains the two centrioles, and the cilia and flagellae that allow cell movement are also made of microtubules.

Fig.1
Centrosome, centrioles and microtubule

Centriole: Important in mitosis for formation of the spindle apparatus. Spherical or rod-shaped structures of 0.3-0.5 nm. Part of the centrosome (small organelle near the nucleus). Source of the microtubules that form the cytoskeleton of the cell.

Each cell has a pair of centrioles made of nine sets of 3 microtubules.

3D animation: The cytoskeleton

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