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Encyclopedia > Macromolecule
Illustration of a polypeptide macromolecule
Illustration of a polypeptide macromolecule

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. Image File history File links Download high resolution version (984x629, 220 KB) Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (984x629, 220 KB) Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... Biochemistry (from Greek: , bios, life and Egyptian kēme, earth[1]) is the study of the chemical processes in living organisms. ... A biopolymer is a polymer found in nature. ... A nucleotide is a chemical compound that consists of a heterocyclic base, a sugar, and one or more phosphate groups. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Lactose is a disaccharide found in milk. ... Some common lipids. ... A macrocycle is, as defined by IUPAC, In the chemical literature, organic chemists may consider any molecule containing a ring of seven, fifteen, or any arbitrarily large number of atoms to be macrocyclic. ...

Contents

Usage

The term macromolecule was coined by Nobel laureate Hermann Staudinger in the 1920s. 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[1]. The Nobel Prizes (Swedish: ), as designated in Alfred Nobels will in 1895, are awarded for physics, chemistry, physiology or medicine, literature, and peace. ... Hermann Staudinger (March 23, 1881 in Worms- Sept. ... 1920 (MCMXX) was a leap year starting on Thursday. ... Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, knowledge), also referred to as the biological sciences, is the study of living organisms utilizing the scientific method. ... For other uses, see Chemistry (disambiguation). ... In physics, chemistry, and biology, intermolecular forces are forces that act between stable molecules or between functional groups of macromolecules. ... Covalent redirects here. ...


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[2]. The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ...

Structure of a polyphenylene dendrimer macromolecule reported by Müllen,k and coworkers in Chem.-Eur. J., 2002, 3858-3864.

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 [[proteinsegt}} Image File history File links Metadata Size of this preview: 552 × 600 pixelsFull resolution (639 × 694 pixel, file size: 152 KB, MIME type: image/jpeg) This is a picture generated from crystal structure data reported by Roland. ... Image File history File links Metadata Size of this preview: 552 × 600 pixelsFull resolution (639 × 694 pixel, file size: 152 KB, MIME type: image/jpeg) This is a picture generated from crystal structure data reported by Roland. ... A dendrimer is a molecule with a form like the branches of a tree. ... Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations). ... The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ...


Properties

Substances that are composed of macromolecules often have unusual physical properties. The properties of liquid crystals and such elastomers as rubber are examples. 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. Schlieren texture of Liquid Crystal nematic phase Liquid crystals are substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. ... The term elastomer is often used interchangeably with the term rubber, and is preferred when referring to vulcanisates. ... This does not cite any references or sources. ... Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American quantum chemist and biochemist. ... Base pairs, of a DNA molecule. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ...


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. For other uses, see Salt (disambiguation). ... This article is about the electrically charged particle. ... Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it) Denaturation is the alteration of a protein or nucleic acids shape through some form of external stress (for example, by applying heat, acid or alkali), in such a way that it will no...


References

  1. ^ van Holde, K.E. Principles of Physical Biochemistry Prentice Hall: New Jersey, 1998
  2. ^ http://www.iupac.org/reports/1996/6812jenkins/6812basicterms.pdf

External links


  Results from FactBites:
 
Macromolecule (209 words)
Literally speaking, a macromolecule is a large molecule, and may be a protein, a lipid, a nucleic acid, or a polysaccharide (i.e., a starch).
Carbon nanotubes are macromolecules, as are the larger sheets of graphite.
A macromolecule may achieve its size through being a single polymeric chain, or it may be composed of multiple smaller units that are noncovalently bound.
Macromolecule - Wikipedia, the free encyclopedia (404 words)
A macromolecule is a large molecule with a large molecular mass, but generally the use of the term is restricted to polymers and molecules which structurally include polymers.
The term macromolecule is also sometimes used to refer to aggregates of two or more macromolecules held together by intermolecular forces rather than by chemical "bonds".
According to IUPAC recommendations the term macromolecule is reserved for an individual molecule, and the term polymer is used as to denote a substance composed of macromolecules.
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