Macromolecule: Definition, Structure, Physical Properties and Functions

This class of molecules is sometimes called biomacromolecules or biopolymers.

The term macromolecule is used ambiguously to describe a molecule composed of any “large number” of atoms, but it is increasingly understood to mean only those molecules that comprise at least 100 atoms.

The bulk of macromolecules are found in biology and biochemistry, in the form of long chains of proteins and nucleic acids like DNA.

Many of the differences between organisms can be traced to the different configurations of macromolecules within the organism.

Within a single organism, there can be even large differences between assorted macromolecules.

It is rare to see a metal or crystal called a macromolecule, even when there are more than 100 atoms bound together.

Most commonly, the term is applied to plastics, where there are countless examples of the type.

Macromolecules can be found in plastics, rubber, and diamonds.


Macromolecules are large structures made up of atoms and smaller molecular structures.

Most macromolecules are polymers, which are long chains of subunits called monomers.

These subunits are often very similar to each other, and for all the diversity of polymers, and living things in general, there are only about 40 to 50 common monomers.

These constituent parts of the macromolecule known as monomers, despite being a very small set, when linked in different configurations, produce an extremely large variety of macromolecules.

Physical properties

Macromolecules are not simply an arbitrary distinction, as they exhibit many physical properties that distinguish them from ordinary molecules.

A particularly interesting property is its inability to dissolve in solution without external assistance (in the form of ions or salts, for example).

Another is its tendency to break easily, often leading to erroneous assumptions, such as a claim in the 1950s that DNA could never be more than 5,000 base pairs.

Although we now know this to be terribly wrong (DNA strands can be in the tens of millions of base pairs), at the time scientists were breaking DNA strands every time they put them under a microscope.

In use, “macromolecule” can also refer to aggregates of multiple macromolecules, essentially producing super-macromolecules.

These macromolecules are held together not by chemical bonds , but rather by intermolecular forces.

Correctly, the terms of complexes of macromolecules should be used when we refer to these combinations and as subunits to the constituent components.


Macromolecules play important and sometimes vital roles in creating and sustaining life.

While there are many types of macromolecules, those that are fundamental to the existence of life, called biopolymer macromolecules, can be organized into four categories: proteins, nucleic acids, carbohydrates, and lipids.

Proteins (amino acid)

The macromolecules of polypeptides have the main function of keeping the body functioning. They are enzymes, structures, receptors, transport, among others.

Proteins, like all macromolecules, are formed from smaller units that combine and join together to form a larger molecule.

Amino acids, which are smaller, simpler molecules, connect end-to-end to form proteins.

Twenty-one different amino acids are essential for life; there are many different combinations that can be formed from this set.

As such, there are many different possible proteins, this varies depending on the number of sets of amino acids in a protein, each with its own particular function, ranging from attacking antigens in the blood to regulatory metabolism and food particles.

Proteins are involved in most life processes.

Nucleic acids (nucleotide)

These polynucleotides have the function of storing and transferring information.

Nucleic acids, deoxyribonucleic acid and ribonucleic acid, contain and describe the genetic code of life.

As macromolecules, nucleic acids serve as a detailed instruction manual for the development of the body and the functioning of each cell.

Nucleic acids form the sugar 2-deoxyribose, a phosphate group, and one of the four base molecules.

Different combinations of the four base molecules along the deoxyribonucleic acid chain encode certain amino acids, which eventually connect to form proteins.

While deoxyribonucleic acid contains the raw genetic information for life, ribonucleic acid passes messages between deoxyribonucleic acid and the cell.

Carbohydrates (monosaccharides)

The macromolecules of polysaccharides have the function of storing chemical energy and receptors, and they also make up the structure of the plant cell wall.

Found in many energy-providing foods, carbohydrates assist the nervous system, muscles, and the body in general function.

A group of polymers that contain nothing but carbon, hydrogen, and oxygen.

The human body breaks down carbohydrates into their building blocks, which it then uses to fuel cells and maintain bodily processes.

The carbohydrate list is extensive and includes all sugars and starches.

Lipids (glycerol, fatty acids)

These macromolecules are represented by fats, oils, waxes, phospholipids and steroids, they are part of the structure of the protective membranes around cells, they provide essential vitamins, and they store energy, they also have insulation functions.

While carbohydrates supply the body with immediate energy, lipids, a class of macromolecules, provide long-term energy storage.

There are dozens of lipids, which are very important for various organisms.