Current Status
Not Enrolled
Get Started

Biomolecules are organic molecules produced by cells and living organisms. The four major types of biomolecules are carbohydrates, proteins, lipids, and fats.

All living forms — bacteria, algae, plant, and animals —  are made of these macromolecules.

This course covers:

  • What biomolecules are, classify them and understand their functions.
  • Various kinds of carbohydrates and their functions.
  • Proteins and their functions.
  • Lipids and their functions.
  • DNA and RNA and their functions.

Polymers are formed by linking monomers through covalent bonds.

Table below shows four major classes of macromolecules and their monomers.

Monomer Polymer
Monosacchrides Polysaccrides
Amino acids Protein
Fatty acid Diglycerides, triglyerides
Nucleotide Nucleic acid

Diglycerides, triglyerides are not formed by cross linking, however, they are considered as monomers that form fatty acid.

Classification of Biomolecules

Biomolecules are categorized into four major classes (Figure 1). They work together to perform specific functions and to build important structural features of cells.

Classification of Biomolecules
Figure 1. Classification of Biomolecules

Functions of Biomolecules


Carbohydrates are an excellent source of fuel and energy. They aid in functioning of our brain, heart and nervous, digestive and immune system.

These are often built into long chains by joining together smaller units. The general term for a single unit is monomer. Multiple units of monomers are joined together to form polymer.

Amino acids and Proteins

Various amino acids and proteins carry out specific functions inside cells. They act as enzymes to catalyze reactions all over the body.

Some proteins are responsible for the structural support and movement, whereas, others help fight against germs and infections.


Lipids do not dissolve in water and are hydrophobic. Like the carbohydrates, lipids are composed primarily of carbon, hydrogen and oxygen.

They help in energy storage and form structural component of a cell. Lipid hormones, sterols, mediates communication between cells, whereas, steroid hormones are important regulators of cell activity.

Oils and waxes provide protection by coating areas of the body that could be infected by germs. They are useful in maintaining cell contact and controling cell activity.

Nuclei Acid

Nucleic acids are polymers of nucleotides. DNA and RNA are the two major types of nucleic acids. Both of these molecules are polymers.

They are also composed of monomer subunits, similar to carbohydrates and proteins.

Nucleic acids carry genetic information in the cell and help in synthesis of proteins through the process of translation and transcription.

External References