Ex. 4 Physico-Chemical Properties of Protoplasm

Physico-chemical Properties of the Protoplasm

Physical Properties of the Protoplasm Chemical Properties of the Protoplasm Translocation of Materials in the Cell

Protoplasm 

The protoplasm is the living substance of the cell.  Cytoplasm – protoplasm surrounding the nucleus  Nucleoplasm – protoplasm inside the nucleus

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It may vary from one cell to another or from one organism to another but all have the same basic properties.

Physical Properties of the Protoplasm

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The protoplasm is jelly-like, translucent, colorless, slimy and viscous.

Brownian Movement (Robert Brown in 1827) 

The protoplasm exhibits the Brownian Movement  The zigzag motion of suspended colloidal particles in the colloidal solution is due to the incessant bombarding with the molecules of the liquid.  It contributes to the diffusion of colloid particles through the solution.

Brownian Movement (Robert Brown in 1827) 

temperature =

rapid movement of molecules viscosity of the protoplasm

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viscosity = gel-like state viscosity = sol-like state

Chemical Properties of the Protoplasm 

The protoplasm is composed of:  Inorganic compounds • Water, CO2, acids, bases, salts and minerals 

Organic compounds • Carbohydrates • Fats • Proteins

Chemical Properties of the Protoplasm 

Tests for the presence of carbohydrates  Monosaccharides – Benedict’s solution  Polysaccharides – Iodine

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Tests for the presence of fats  Grease Spot Test  Dye Test

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Tests for the presence of proteins  Coagulation  Biuret test

Translocation of Materials in the Cell 

Diffusion through a membrane  Simple passive diffusion • Small molecules pass through the lipid bilayer of a cell membrane 

Facilitated diffusion • Proteins in the membrane allow entry and exit of specific molecules that are not able to directly diffuse through the cell membrane

Translocation of Materials in the Cell 

Osmosis 

Diffusion of water through the semi-permeable membrane • Hypertonic: high concentration of solute outside the cell; the cell tends to shrink • Hypotonic: low concentration of solute outside the cell; the cell tends to burst • Isotonic: equal concentrations of solute inside and outside the cell; size of cell remains