Composition, Structure, And Function Of Biomolecules

Composition, Structure, And Function Of Biomolecules


The molecules found in the organisms are called biomolecules and they obey the same laws of physics and chemistry.

Biomolecules have curious optical activity.

They rotate the plane of polarisation of independent light.

Organic molecules produced abiologically lack this property. Products of biological origin prefer the odd number of C atom per molecule.

The cellular pool is the collection of various types of molecules in a cell. Elements do not occur free but combine to form various organic and inorganic compounds.

The inorganic molecules generally occur in the aqueous phase.

The organic molecules are found both in aqueous and nonaqueous phase.The aqueous phase contains molecules and ions dissolved in water.

It is found in two forms,

True or molecular solution and colloidal solution.

Non-aqueous phase has organic molecules as components of cell membrane, cell wall, chromosomes and other organelles. The cellular pool is mainly constituted by:

  1.  Inorganic materials like salts, mineral ion, and water.
  2. Organic compounds as carbohydrate, lipids amino acids, proteins, nucleotides, nucleic acids and vitamins.

Organic and inorganic compounds occur in the ratio 9:1.

Few organic molecules show their presence in the form of colloids in the aqueous intracellular fluid. Still, others are found in non-aqueous phases like cell wall and biomembranes.

The intracellular composition of the cell has been found to be different to that of extracellular fluid. Plasma membrane maintains this distinction due to its selectively permeable nature.

Plasma membrane maintains this distinction due to its selectively permeable nature.

Small molecules of cellular food basically have the following characteristics :

  1. Low molecular weight
  2. Simple molecule conformation
  3. Higher solubility

Small molecules include water, minerals, amino acids, sugars, lipids, and nucleotides.

The protoplasm of a plant or animal cell contains 75 to 85% of water, 10-20% of proteins, 2 to 3 % of lipids, 1-2% of carbohydrates and 1-1.5% of inorganic substances.

Some Biomolecules :