Cytoskeleton

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Name :- Cytoskeleton

Properties :

  • It is an cellular organelle present throughout the cytoplasm.
  • It is a complex network of structures with varying sizes.
  • Cytoskeleton is consists of three major protein components i.e. microtubule, intermediate filaments and microfilaments.
Microtubules :
  • These are the straight, hollow and tubular structures. 
  • These organelles are arranged in different bundles without the limiting any membrane. 
  • Each tubules has 20-30 nano-meter diameter and length varies, it may be 1000 times more than the thickness. 
  • Microtubules are formed by bundles of globular protein called tubulin. Tubulin has two subunits i.e. alpha and beta.
Intermediate Filaments (IF) :
  • IF form a network around the nucleus and extend to the periphery of the cell.
  • Diameter of each filament is about 10 nano-meter.
  • IF are formed by rope-like protein polymers (fibrous proteins)
  • IF are divided into five subclasses :-
    • Keratins (in epithelial cells)
    • Glial flaments (in astrocytes)
    • Neurofilaments (in nerve cells)
    • Vimentin (in many types of cells)
    • Desmin (in muscle fibers)
Microfilaments :
  • These are long and fine thread-like structures.
  • It's diameter is about 3-6 nano-meter.
  • These are present throughout the cytoplasm.
  • These are formed by non-tubular contractile proteins (actin and myosin).
  • Microfilaments contain only actin molecules when these are present in ectoplasm.
  • Microfilaments contain actin and mysosin molecules when these are present in endoplasm.

Cytoskeleton

Functions of ... 

Cytoskeleton :

  1. It determines the shape of the cell and gives support to the cell.
  2. It is essential for cellular movements.
  3. It is responsible for response of the cell to external stimuli.
  4. It helps in cell division.

Microtubules : It may function alone or join with other proteins to form complex structures like cilia, flagella or centrioles and perform various functions.

  1. Determine the shape of the cell.
  2. Give structural strength to the cell.
  3. Act like conveyer belt which allow the movement of granules, vesicles, protein molecules and some organelles like mitochondria to different part of the cell.
  4. Form the spindle fibers which separates the chromosomes during mitosis.
Intermediate filaments :
  1. Helps to maintain the shape of the cell.
  2. It connect the adjacent cells through desmosomes.
Microfilaments : 
  1. Give structural strength to the cell.
  2. Provide resistance to the cell against the pulling forces.
  3. Responsible for cellular movements like contraction, gliding and cytokinesis (partition of cytoplasm during cell division).

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