Macromolecules are any molecules which contain a very large number of atoms. There are four main classifications of macromolecules: carbohydrates, lipids, nucleic acids, and proteins.
Carbohydrates
Carbohydrates are organic compounds made up of carbon, hydrogen and oxygen atoms. In carbohydrates, these three elements appear in the common ratio of 1 carbon atom to 2 oxygen atoms to 1 oxygen atom.
The main function of carbohydrates is short-term energy storage in the form of sugar. Carbohydrates such as starch in plants and glycogen in animals are also used for the intermediate-term storage of energy. Other carbohydrates act as structural components in cells, such as cellulose which is found in the cell walls of plants.
Lipids
Lipids are a broad group of molecules which include fats, waxes, sterols and phospholipids. The main functions of lipids include energy storage, structural components of cell membranes and signaling molecules.
Nucleic Acids
Nucleic acids are built up of nucleotides. An individual nucleotide is made up of three distinct components bonded together. The three components of a nucleotide are: a nitrogen-containing base, a 5-carbon sugar (either ribose sugar or deoxyribose sugar) and a phosphate group. The nucleotides are then bonded together by phosphodiester bonds to form the nucleic acid macromolecule.
The two most common nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA and RNA make up all the genetic material in our body.
Proteins
The basic building blocks of proteins are amino acids. Amino acids are bonded together by peptide bonds between the carboxyl group of one amino acid and the amino group of another amino acid. Individual amino acids are called residues. There are 20 different amino acids which combine in sequences of hundreds or thousands of amino acids to form proteins.
Many proteins are enzymes which catalyze reactions. Proteins also have functions including: cell signalling, immune responses, structural support or bodily movement.
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This article was written for you by Mia, one of the tutors with Test Prep Academy.