Cytoskeleton and Its Components

September 25, 2021

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:

Image source: Pediaa.com

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

Function of Intermediate Filaments

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

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.

References