Cytoskeleton – Class 11 | Chapter – 8 | Short Notes Series PDF

The cytoskeleton is a network of filaments and tubules that stretches throughout a cell, through the cytoplasm, which is all the substance within a cell except the nucleus itself. It is found in all cells, although the proteins it is made of vary from organism to organism. The cytoskeleton supports the cell, shapes the organelles, organizes and teters them, and plays a role in molecule transport, cell division and cell signaling.

Structure of Cytoskeleton

A cytoskeleton structure comprises the following types of fibres:

  • Microfilaments
  • Microtubules
  • Intermediate Filaments


Microtubules appear like small, hollow, round tubes with a diameter of about 24 nanometers. They are made up of a protein, tubulin. Thirteen tubulins link to form a single tube. Microtubules are very dynamic structures, which reveal that they can change quickly. They keep growing or shrinking steadily. These help in transporting cellular materials and dividing chromosomes during cell division.


Microfilaments are thread-like protein fibres, 3-6 nm in diameter. They are particularly found in muscle cells. They consist of the protein actin, responsible for muscle contraction. These are also responsible for cellular movements including cytokinesis, contraction, and gliding.

Intermediate Filaments

The intermediate filaments are about 10 nm in diameter and provide tensile strength to the cell. They facilitate the formation of keratins and neurofilaments.

The cytoskeleton is also made up of certain motor proteins. These include:


These proteins move along the microtubules carrying the cellular components. They pull the organelles along the cell membrane.


These pull the cell organelles towards the nucleus.


These interact with actin protein and are responsible for muscle contractions. They also perform cytokinesis, exocytosis, and endocytosis.

Functions of Cytoskeleton

 The important cytoskeleton functions are mentioned below:

  • It provides shape and support to the cell.
  • It helps in the formation of vacuoles.
  • It holds different cell organelles in place.
  • It assists in cell signalling.
  • It supports intracellular movements like the migration of cell organelles, transportation of vesicles in and out of the cell, etc.

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By Team Learning Mantras