Cellular Micromolecules

Introduction

     At the molecular level all the different types of cells in living organisms are composed of certain chemical substances. The structure and function of the cell and its components are dependent on the molecular structure, arrangement and properties of these chemical constituents. The molecules found in the cells are called biological molecules or biomolecules. The collection of various types of molecules in a cell is known as cellular pool. It consists of water, inorganic substances and organic substances.

Water

     Water is the most abundant compound in the vast majority of cells. It forms about 60 to 90% of the total chemical content of the cell.

Minerals

     Minerals occurring in the living cells form components of various inorganic and organic substances. About 20 different elements form the essential nutrients for the cells. Minerals in the living system occur in two forms (i) compounds or (ii) ions.

Monosaccharides and Oligosaccharides

     Carbohydrates represent a class of biological molecules that are extremely important for cells since they serve as the chief source of energy. Carbohydrates are organic compounds containing carbon, hydrogen and oxygen. Hydrogen and oxygen occur in a carbohydrate molecule in the same ratio as in water (2:1). Hence, carbohydrates are represented by the general empirical formula Cx(H₂O)n.

Lipids

     Lipids are also organic compounds containing carbon, hydrogen and oxygen. However, hydrogen and oxygen occur in a ratio much higher than in water. Lipids form about 3.5% of the total chemical composition of a cell. Lipids are generally insoluble in water but soluble in organic solvents like ether and chloroform.

Amino Acids

     Amino acids are compounds containing carbon, hydrogen, oxygen and nitrogen. They serve mainly as monomers (building blocks) of proteins.

Nucleotides

     Nucleotides are nitrogen containing organic compounds, which form the monomers of nucleic acids that are involved in the information transfer system of the cells. They are also involved in the mechanism of energy transfer in cells.

Summary

     The molecules found in the living systems are called biomolecules. They are represented by the molecules of about 25 elements of the 109 elements known to exist.