AskDefine | Define macromolecules

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Noun

macromolecules
  1. Plural of macromolecule

Extensive Definition

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.

Usage

The 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.

Properties

Substances 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.
macromolecules in Arabic: جزيء كبري
macromolecules in Bosnian: Makromolekula
macromolecules in Czech: Makromolekula
macromolecules in German: Makromolekül
macromolecules in Modern Greek (1453-): Μακρομόριο
macromolecules in Spanish: Macromolécula
macromolecules in Persian: درشت‌ملکول
macromolecules in French: Macromolécule
macromolecules in Galician: Macromolécula
macromolecules in Korean: 고분자
macromolecules in Indonesian: Makromolekul
macromolecules in Italian: Macromolecola
macromolecules in Hebrew: מקרומולקולה
macromolecules in Lithuanian: Makromolekulė
macromolecules in Dutch: Macromolecuul
macromolecules in Japanese: 高分子
macromolecules in Norwegian: Makromolekyl
macromolecules in Norwegian Nynorsk: Makromolekyl
macromolecules in Occitan (post 1500): Macromolecula
macromolecules in Portuguese: Macromolécula
macromolecules in Russian: Макромолекула
macromolecules in Simple English: Macromolecule
macromolecules in Slovak: Makromolekula
macromolecules in Slovenian: Makromolekula
macromolecules in Sundanese: Makromolekul
macromolecules in Swedish: Makromolekyl
macromolecules in Ukrainian: Макромолекула
macromolecules in Urdu: سالمۂ کبیر
macromolecules in Chinese: 高分子
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