The term "molecules of life" refers to the molecules that are essential for the functioning of living organisms. These molecules include carbohydrates, proteins, lipids, and nucleic acids.

They are called organic molecules because they contain carbon atoms. Carbon is a unique element that can form a wide variety of bonds with other atoms, which allows for the creation of complex and diverse molecules.

In contrast, inorganic molecules do not contain carbon atoms and are generally simpler in structure. Therefore, the presence of carbon atoms is a defining characteristic of organic molecules and is why molecules of life are often referred to as organic molecules.