Macromolecule

Macromolecule is a term used in biochemistry for a very large molecule, such as a protein, commonly composed of the polymerization of smaller subunits called monomers. They are typically composed of thousands of atoms or more. The most common macromolecules in biochemistry are biopolymers (nucleic acids, proteins, and carbohydrates) and large non-polymeric molecules (such as lipids and macrocycles), synthetic fibers as well as experimental materials such as carbon nanotubes.

Structure

Macromolecules often have a complex structure. They can be composed of covalently bonded atoms with definite, repeating structure, or they may be composed of a complex mixture of different atoms. Most macromolecules are made from single subunits, or building blocks, called monomers. The monomers may be the same, as in polyethylene, or different, as in a copolymer.

Types of Macromolecules

There are four major types of macromolecules—proteins, carbohydrates, nucleic acids, and lipids.

Proteins

Proteins are a primary type of macromolecules. They are composed of amino acids, which are monomers. Proteins perform a vast array of functions within organisms, including catalyzing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another.

Carbohydrates

Carbohydrates are another type of macromolecule. They are composed of sugar molecules, which are monomers. Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy and as structural components.

Nucleic Acids

Nucleic acids are macromolecules that store genetic information in cells. They are composed of nucleotides, which are monomers. There are two types of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Lipids

Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others.

See Also

• Polymer
• Monomer
• Biopolymer
• Polyethylene
• Copolymer

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  A 3D model of a protein structure.
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  Chemical structure of raspberry ellagitannin.
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  A dendrimer molecule from a 2002 chemistry journal.