Biomacromolecules – Class 12 | Chapter – 9 | Biology Short Notes Series PDF

Biomacromolecules: Any carbon-containing molecule, i.e., organic compounds present in a living cell, is called a biomolecule. Based on the molecular weight, biomolecules are classified into two, namely micromolecules and macromolecules.

Micromolecules are those biomolecules which have a molecular weight of less than 10,000 Dalton (Da). This includes the primary metabolites and secondary metabolites. Micromolecules are acid soluble, and their molecular weights range from 18 to 800 Da.

Macromolecules are biomolecules which are characterized by their acid insoluble property. Proteins, carbohydrates, lipids, and nucleic acids are the macromolecules found in living organisms; they are also called biomacromolecules. They have a molecular weight of more than ten thousand daltons. However, lipids are an exception. Though lipids have a molecular weight of less than 800 Da, they are classified as biomacromolecules because of their acid insoluble property. Hence, lipids are not strictly macromolecules.


Macromolecule Basic Formula, key features Monomer Examples Uses
Proteins  CHON

−NH2 + −COOH +R group


Amino acids Enzymes, some hormones Storage; Signals; Structural; Contractile; Defensive; Enzyme; Transport; Receptors
Lipids  C:H:O

Greater than 2:1 H:O (carboxyl group)

Fatty acid and glycerol Butter, oil, cholesterol, beeswax Energy storage; Protection; Chemical messengers; Repel water
Carbohydrates C:H:O


Monosaccharides Glucose, Fructose, Starch, Glycogen, Cellulose Energy storage; Structure
Nucleic Acids CHONP

pentose, nitrogenous base, phosphate

Nucleotides DNA, RNA Genetic information


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By Team Learning Mantras