A monomer (/ˈmɒnəmər/ MON-ə-mər) (mono-, "one" + -mer, "part") is a molecule that, as a unit, binds chemically or supramolecularly to other molecules to form a supramolecular polymer. Large numbers of monomer units combine to form polymers in a process called polymerization. It is a small molecule of an organic substance. A double bond exists between the individual molecules which are weak. Molecules of a small number of monomer units (up to a few dozen) are called oligomers. The term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex.

*Diglycerides and triglycerides are made from smaller molecules by dehydration synthesis, which is not the same process as the end-to-end linking of similar monomers that qualifies as polymerization; thus, diglycerides and triglycerides are an exception to the term polymer.

Examples: The most common natural monomer is glucose, which is linked by glycosidic bonds into polymers such as cellulose, starch, and glycogen. The term monomer also refers to organic molecules that form synthetic polymers, for example the vinyl chloride monomer, which is used to produce the polymer polyvinyl chloride (PVC).

Amino acids are natural monomers that polymerize at ribosomes to form proteins. Nucleotides, monomers found in the cell nucleus, polymerize to form nucleic acidsDNA and RNA. Glucose monomers can polymerize to form starches, glycogen or cellulose; xylose monomers can polymerise to form xylan. In all these cases and is thus not pliable, a hydrogen atom and a hydroxyl (-OH) group are lost to form H2O, and an oxygen atom links each monomer unit. Due to the formation of water as one of the products, these reactions are known as dehydration.

Isoprene is a natural monomer and polymerizes to form natural rubber, most often cis-1,4-polyisoprene, but also trans-1,4-polymer

The lower molecular weight compounds built from monomers are also referred to as dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, nonamers, decamers, dodecamers, eicosamers, etc. if they have 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, or 20 monomer units, respectively. Any number of these monomer units may be indicated by the appropriate Greek prefix. Larger numbers are often stated in English or numbers instead of Greek; e.g., a 20-mer is formed from 20 monomers. Molecules made of a small number of monomer units, up to a few dozen, are called oligomers.

This page was last edited on 12 December 2017, at 21:00.
Reference: under CC BY-SA license.

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