Cytoskeleton and Its Components

  • The cellular organelle present throughout the cytoplasm is called cytoskeleton.
  • The shape of the cell is determined by it and also gives support to the cell.
  • It is of varying sizes and is a complex network of structures.
  • It also helps in the cellular movements and also gives response to the cell to external stimuli.
  • It consists of three major protein components that are as follows:

Difference Between Cytoplasm and Cytoskeleton | Definition, Structure, Function, Similarities

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A) Microtubule

B) Intermediate filaments

C) Microfilaments

A) Microtubules

  • These are the narrow, straight, hollow and tubular structure present in the cytoskeleton.
  • These structures are arranged in different bundles and are without the limiting membrane.
  • It has a diameter of 20-30nm and the length varies which is more than 1000 times than the thickness.
  • Bundles of globular protein called tubulin forms the microtubules structurally where tubulin contains two subunits called α-subunit and β-subunit.

Functions of microtubules

  • Microtubules may function singly or join with other proteins to form more complex structures like cilia, flagella or centrioles and perform various functions.
  • They help to determine the shape of the cell.
  • Structural length to the cell is provided by microtubules.
  • They act as conveyer belts allowing the movement of granules, vesicles, protein molecules and some organelles like mitochondria to different parts of the cell.
  • They also form the spindle fibres that help to separate chromosome during mitosis.
  • They also allow the movement of centrioles and the complex cellular structures like cilia.

B) Intermediate Filaments

  • They are the structures forming a network around the nucleus extending to the periphery of the cell.
  • They are about 10 nm in diameter and are formed by rope-like polymers which are made up of fibrous proteins.

Subclasses of intermediate filaments

  • There are five subclasses of intermediate filaments. They are:
  1.  Keratins (in epithelial cells)
  2. Glial filaments (in astrocytes)
  3.  Neurofilaments (in nerve cells)
  4.  Vimentin (in many types of cells)
  5. Desmin (in muscle fibres)

Function of Intermediate Filaments

  • Intermediate filaments help in maintaining the shape of the cell and also connecting the adjacent cells through desmosomes.

Cytoskeleton - Javatpoint

Image Source: Javatpoint

C) Microfilaments

  • They are long, fine thread like structures having a diameter of about 3 to 6 nm.
  • Non-tubular contractile proteins called actin and myosin make these filaments where actin is more abundant than myosin.
  • They are present throughout the cytoplasm and contain only actin molecules in ectoplasm.
  • The microfilaments present in the endoplasm contains both actin and myosin molecules.

Functions of the microfilaments

  • Cell gets structural length due to microfilaments.
  • They provide resistance to the cell against the pulling forces.
  • Cellular movements like contraction, gliding and cytokinesis (partition of cytoplasm during cell division) are also possible due to presence of microfilaments.




Cytoskeleton and Its Components