Introduction to Biological Macromolecules

Biological Macromolecules Overview

Biological macromolecules are large, complex molecules that play essential roles in all aspects of life.
There are four main types of biological macromolecules: proteins, nucleic acids, carbohydrates, and lipids.
These macromolecules are composed of smaller subunits called monomers. When monomers join together, they form chains called polymers.

Proteins

Proteins are made of monomers known as amino acids.
Amino acids share a common structure but have a variable side chain, also known as an R-group, which determines what type of amino acid it is.
The sequence of amino acids defines a protein’s structure and specific function.
Proteins serve as enzymes, transporters, antibodies, structural support, and perform many other functions within the cell.

Nucleic Acids

Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers called nucleotides.
Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
Sequences of nucleotides in DNA determine the genetic information for organisational development and functioning.

Carbohydrates

Carbohydrates are made from monomers called monosaccharides, simple sugars.
They provide and store energy, form structural components, and are involved in cell-cell recognition.
Common examples include glucose (energy source) and cellulose (structural function in plants).

Lipids

Lipids are the only class of macromolecules that are not true polymers - they’re made of glycerol and fatty acids.
These molecules are hydrophobic (water-hating), so they are insoluble in water.
Lipids provide long-term energy storage, insulation, cushion vital organs, and compose cell membranes (as phospholipids).

Functional Groups

Functional groups are groups of atoms that provide specific properties and behaviours to organic compounds.
These include hydroxyl (–OH), carboxyl (–COOH), amino (–NH2), and phosphate (–PO4) groups, and are relevant to the structure of macromolecules.

Dehydration Synthesis and Hydrolysis

Dehydration synthesis (condensation) is the process of combining monomers to form polymers by removing a molecule of water.
Hydrolysis is the opposite process, breaking down polymers into monomers by adding a water molecule.
These two processes are critical to the formation and breakdown of biological macromolecules in organisms.

Learning these concepts provides a foundational understanding of how life’s chemistry is organized and plays a central role in countless biological processes.