Cytoplasm has number physical and biological properties:
1. Physical properties:
The colloidal nature of cytoplasm is responsible for the various physical properties a colloidal system may be defined as a system of liquid medium containing suspends particles varying in diameter from 1/1,000,000 to 1/10,000 nm. Some of the physical properties are follows.
Phase reversal:
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Cytoplasm may be differentiated into a sol state and gel state. Sol state is the liquid state and the gel state is the semi solid state. These two phases are interchangeable. This capacity is known as phase reversal.
Elasticity:
Depending on the circumstances, the cytoplasm can extend or contract subject to a certain limit. This is known as elasticity.
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Cohesiveness:
The suspended particles in cytoplasm have mutual attraction, thus exhibiting cohesiveness.
Contractility:
It is the capacity of peripheral cytoplasm to absorb or remove water from cell to the exterior. This is manifested very well by guard cells.
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Viscosity:
The suspended particles of cytoplasm are responsible for its viscous nature.
Brownian movement:
The suspended particles of cytoplasm are in a state of to and fro movement called Brownian movement.
In addition to this, cytoplasm also exhibits movements (seen in the Plasmodium of slime molds) and ‘cyclosis or streaming movements (seen in the leaf cells of Elodea).
2. Biological properties:
Growth, respiration, excretion, nutrition, reproduction, metabolism, irritability etc., are some of the important biological activities of cytoplasm.
Chemical composition of cytoplasm:
90% of cytoplasm is water. The remaining 10% is constituted by organic and inorganic compounds.
About 40 or more inorganic constituents are found in cytoplasm. These are found in the form of ions (either cations or anions). Some of the common inorganic constituents are – Oxygen (62%), Hydrogen (10%), Carbon (18%) and Nitrogen (3%). The less common inorganic constituents are Calcium (0.25%), Phosphorus (1.2%), Sodium (0.1%), Magnesium (0.7%), Iodine (015%) and Chlorine (0:15%).
Among the various organic substances proteins, carbohydrates, lipids, hormones, vitamins and nucleic acids are most important.