Physical of the protoplasm:
Many theories have been put forth to explain physical nature of the protoplasm. Out of them, follow ing five theories are main and all of them are applicable-
- Alveolar theory – It was propounded by Butchilli (1882). According to it, the protoplasm is an emulsion with dispersed minute drops or alveoli. This theory is more close to the modern thinking.
- Granular theory – It is proposed by Altmann (1893). According to it, the protoplasm consists of minute granules.
- Reticular theory – It was proposed by Hanslein, Klein and Carnoy (1898). According to it, the proplasm consists of network of fibrils.
- Fibrillar theory – It was propounded by Flemming (1894). According to it, the protoplasm consists of minute fibres.
- Colloidal theory – It was prposed by Wilson Fisher (1894). The protoplasm is a crystallocolloidal solution & polyphasic colloidal system.
It has a dispersion phase and colloidal particles. It is the most accepted theory.
The protoplasm respond external stimuli such as low to high temperature, chemical, light etc. It exhibits following vital activities –
- Movement
- Nutrition
- Metabolism
- Respiration
- Growth
- Excretion
- Reproduction
- Life cycle
Chemical of the protoplasm:
The chemical composition of the protoplasm is complex and its chemical analysis is not possible in living state. It consists of about 50 types of chemical compounds . Some of them are as follows –
Water 75 to 85%
Proteins 7 to 9%
Carbohydrates 2 to 2.5%
Lipids 1 to 1.5%
Inorganic substances 1 to 1.5%
RNA 0.7%
DNA 0.4%
The protoplasm of some cells eg. aquatic plants, brain cells may have 95% water (maximum).
In seed cells, the water contents is 10 to 15% and in bone cells is only 5% (minimum). The inorganic substance are found in the form of ions. Calcium, potassium, magnesium. Iron etc are positive ions and nitrate, sulphate, bicarbonate, chloride etc. are negative ions.