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macromolecule reported by Müllen and coworkers in Chem.-Eur. J., 2002, 3858-3864.]] The literal definition of the term macromolecule implies any large Molecule . In the context of Science and Engineering , the term may be applied to conventional Polymers and Biopolymers (such as DNA ) as well as non-polymeric molecules with large molecular mass such as Lipids or Macrocycles . However, other large networks of atoms, such as Metal lic covalent networks or Fullerenes , are not generally described as macromolecules. The term macromolecule was coined by Nobel Laureate Hermann Staudinger in the 1920 s. USAGE The use of the term macromolecule to describe different forms of compounds of molecules varies subtly from discipline to discipline. Living things are composed of macromolecules like proteins, carbohydrates and lipids. From the strict perspective of Chemistry , a "molecule" consists of a number of atoms linked by covalent bonds. In Biology and Biochemistry , however, the term macromolecule may refer to aggregates of two or more macromolecules held together by Intermolecular Force s rather than Covalent Bond s but which do not readily dissociate. van Holde, K.E. ''Principles of Physical Biochemistry'' Prentice Hall: New Jersey, 1998 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. Link . DESCRIBING 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 . UNUSUAL PHYSICAL PROPERTIES Substances that are composed of macromolecules often have unusual physical properties. The properties of Liquid Crystal s and such Elastomer s 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 Pair s. This is because biochemists were inadvertently and consistently breaking their samples into pieces. In fact, the DNA of Chromosome s 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 Salt s or particular Ion s to dissolve in water. Proteins will Denature if the solute concentration of their solution is too high or too low. REFERENCES EXTERNAL LINKS
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