macromolecule n : any very large complex molecule; found only in plants and animals [syn: supermolecule]
- Italian: macromolecola
The term macromolecule by definition implies "large molecule". In the context of biochemistry, the term may be applied to the four conventional biopolymers (nucleotides, proteins, carbohydrates, and lipids), as well as non-polymeric molecules with large molecular mass such as macrocycles.
UsageThe term macromolecule was coined by Nobel laureate Hermann Staudinger in the 1920s although his first relevant publication on this field only mentions high molecular compounds (in excess of 1000 atoms). . At that time the phrase polymer as introduced by Berzelius in 1833 had a different meaning from that of today: it simply was another form of isomerism for example with benzene and acetylene and had little to do with size .
Usage of the term to describe different forms of large molecules varies among the disciplines. For example, while biology refers to macromolecules as the four large molecules living things are composed of, from the perspective of chemistry, the term may refer to aggregates of two or more macromolecules held together by intermolecular forces rather than covalent bonds but which do not readily dissociate.
According to the recommended IUPAC definition, the term macromolecule as used in polymer science refers only to a single molecule. For example, a single polymeric molecule is appropriately described as a "macromolecule" or "polymer molecule" rather than a "polymer", which suggests a substance composed of macromolecules.
Because of their size, macromolecules are not conveniently described in terms of stoichiometry alone. The structure of simple macromolecules, such as homopolymers, may be described in terms of the individual monomer subunit and total molecular mass. Complicated biomacromolecules, on the other hand, require multi-faceted structural description such as the hierarchy of structures used to describe proteins.
PropertiesSubstances that are composed of macromolecules often have unusual physical properties. Although too small to see, individual pieces of DNA in solution can be broken in two simply by suctioning the solution through an ordinary straw. This is not true of smaller molecules. The 1964 edition of Linus Pauling's College Chemistry asserted that DNA in nature is never longer than about 5000 base pairs. This is because biochemists were inadvertently and consistently breaking their samples into pieces. In fact, the DNA of chromosomes can be tens of millions of base pairs long.
Another common macromolecular property that does not characterize smaller molecules is the need for assistance in dissolving into solution. Many require salts or particular ions to dissolve in water. Proteins will denature if the solute concentration of their solution is too high or too low.
macromolecule in Arabic: جزيء كبري
macromolecule in Bosnian: Makromolekula
macromolecule in Czech: Makromolekula
macromolecule in German: Makromolekül
macromolecule in Modern Greek (1453-): Μακρομόριο
macromolecule in Spanish: Macromolécula
macromolecule in Persian: درشتملکول
macromolecule in French: Macromolécule
macromolecule in Galician: Macromolécula
macromolecule in Korean: 고분자
macromolecule in Indonesian: Makromolekul
macromolecule in Italian: Macromolecola
macromolecule in Hebrew: מקרומולקולה
macromolecule in Lithuanian: Makromolekulė
macromolecule in Dutch: Macromolecuul
macromolecule in Japanese: 高分子
macromolecule in Norwegian: Makromolekyl
macromolecule in Norwegian Nynorsk: Makromolekyl
macromolecule in Occitan (post 1500): Macromolecula
macromolecule in Portuguese: Macromolécula
macromolecule in Russian: Макромолекула
macromolecule in Simple English: Macromolecule
macromolecule in Slovak: Makromolekula
macromolecule in Slovenian: Makromolekula
macromolecule in Sundanese: Makromolekul
macromolecule in Swedish: Makromolekyl
macromolecule in Ukrainian: Макромолекула
macromolecule in Urdu: سالمۂ کبیر
macromolecule in Chinese: 高分子