kids encyclopedia robot

Biomolecule facts for kids

Kids Encyclopedia Facts
A representation of the 3D structure of myoglobin, showing alpha helices, represented by ribbons. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a Nobel Prize in Chemistry.

A biomolecule or biological molecule is a loosely used term for molecules present in organisms that are essential to one or more typically biological processes, such as cell division, morphogenesis, or development. Biomolecules include large macromolecules (or polyanions) such as proteins, carbohydrates, lipids, and nucleic acids, as well as small molecules such as primary metabolites, secondary metabolites and natural products. A more general name for this class of material is biological materials. Biomolecules are an important element of living organisms, those biomolecules are often endogenous, produced within the organism but organisms usually need exogenous biomolecules, for example certain nutrients, to survive.

Biology and its subfields of biochemistry and molecular biology study biomolecules and their reactions. Most biomolecules are organic compounds, and just four elementsoxygen, carbon, hydrogen, and nitrogen—make up 96% of the human body's mass. But many other elements, such as the various biometals, are also present in small amounts.


Proteins are long-chain molecules built from small units known as amino acids. They are joined together with peptide bonds.

Proteins are essential to all cells. Like other biological macromolecules (polysaccharides and nucleic acids), proteins take part in virtually every process in cells:

Proteins have different functions depending on their shape. They can be found in meat or muscle. They are used for growth and repair, as well as for strengthening the bones. They help to make tissue and cells. They are in animals, plants, fungi, bacteria, and also in the human body.


Carbohydrates are chemical compounds that contain only oxygen, hydrogen and carbon. They are made up of joined-up sugars. Sugars have the general formula Cm(H2O)n, and are also known as saccharides.

Certain carbohydrates are an important storage and transport form of energy in most organisms, including plants and animals.

Carbohydrates are the most common source of energy for the human body. Protein builds tissue and cells in the body. Carbohydrates are very good for energy, but, if a person eats more than needed, the extra is changed into fat through a process called de novo lipogenesis.

If necessary, humans can live without eating carbohydrates because the human body can change fats and proteins into carbohydrates through a process called gluconeogenesis. Some already stored glucose in the liver can be released through another process called glycogenolysis. People of some cultures eat food with very little carbohydrates, but they still remain healthy, such as the Inuits.


A lipid is a type of organic molecule found in living things. It is oily or waxy. Fats are made from lipid molecules. Sources of lipid can be found in algae, seeds, meat, cheese, butter and fish. Lipids are long chains of carbon and hydrogen molecules. Lipids are classified as simple and complex. Examples of complex molecules could be steroids or phospholipids.

A very important biological function of lipids is as lipid bilayers, the basis of many cell membranes. Another function of lipids is to serve as an energy reserve. Lipids can be hydrophobic (non-polar), or amphipatic (containing both polar and non-polar parts).

Nucleic acid

Nucleic acids are large molecules where genetic information is stored. There are two types of nucleic acids: deoxyribonucleic acid, better known as DNA and ribonucleic acid, better known as RNA.

The nucleic acids are made of nucleotides. A nucleotide is made of a nitrogenous base, sugar with five carbon atoms and a phosphate group.

Nucleic acids allow organisms to transfer genetic information from one generation to the next. When a cell divides, its DNA is copied and passed from one cell generation to the next generation.

Images for kids

See also

Kids robot.svg In Spanish: Biomolécula para niños

kids search engine
Biomolecule Facts for Kids. Kiddle Encyclopedia.