11th Class Biology Cell - The Unit Of Life Protoplasm (Proto = First, Plasm = Fluid)

Protoplasm (Proto = First, Plasm = Fluid)

Category : 11th Class

Protoplasm is a complex, granular, elastic, viscous and colourless substance. It is selectively or differentially permeable. It is considered as “Polyphasic colloidal system”.

Discoveries

(1) J. Huxley defined it as “physical basis of life”.

(2) Dujardin (1835) discovered it and called them “sarcode”.

(3) Purkinje (1837) renamed it as “Protoplasm”.

(4) Hugo Von Mohl (1844) gave the significance of it.

(5) Max Schultz (1861) gave the protoplasmic theory for plants.

(6) Fischer (1894) and Hardy (1899) showed its colloidal nature.

(7) Altman (1893) suggested protoplasm as granular.

 

Chemically Composition

Water

75 - 85%

Carbon

20%

Proteins

10 - 25%

Oxygen

62%

Lipids

2 - 3%

Hydrogen

10%

Inorganic Materials

1%

Nitrogen

3%

Trace elements 5% (Ca, P, Cl, S, K, Na, Mg, I, Fe etc.)

 

Maximum water content in protoplasm is found in hydrophytes, i.e., 95% where as minimum in seeds, spores (dormant organs) i.e., 10 – 15%. In animals water is less (about 65%) and proteins are more (about 15%).

Properties of protoplasm

(1) Cyclosis movement : These are shown by protoplasm. These are of two types.

Rotation : In one direction, either clockwise or anticlockwise e.g., Hydrilla, Vallisneria. Found only in eukaryotes.

Circulation : Multidirectional movements around vacuole e.g., Tradescantia.

(2) It shows stimulation or irritability, Sol–gel transformation and Brownian movements.

(3) It is highly viscous and coagulates at 60o C or above or if treated with concentrated acids or bases.

(4) It’s pH is on acidic side, but different vital activities occur at neutral pH which is considered as 7, injury decreases the pH of the cell (i.e., 5.2 – 5.5) and if it remains for a long time, the cell dies.

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