Polymer

∞ generated and posted on 2016.12.22 ∞

Repeating units, often of the same or similar type, that together are linked together to create a longer or larger molecule.

In biology, key polymeric substances are proteins (particularly polypeptides), nucleic acids (i.e., polynucleic acids), and carbohydrates (polysaccharides and to a lesser degree even disaccharides and trisaccharides). Though to a more limited extent, this list can also include lipids. The subunits that make these biomolecular polymers are amino acids (proteins), nucleotides (nucleic acids), and monosaccharides (carbohydrates). See also macromolecule.

Note that the means by which these various subunits are linked together is one of dehydration synthesis. Furthermore, their separation, that is, breakdown into individual subunits, involves the process of hydrolysis. Enzymes that catalyze the hydrolysis of biomolecular polymers include, for example, the proteases that breakdown proteins during digestion.

Figure legend: A linear chain polymer is typically built up by individual additions of subunits known as monomers in a chemical reaction called polymerization. In the course of polymerization individual subunits are converted to what are known as moieties which, in turn, are connected via bonds (as in chemical bonds) or linkages (which also are chemical bonds). Among macromolecules, polypeptides, polysaccharides, and poly-nucleic acids all take this form of linear chain polymers which are built up via the addition of one subunit at a time.

There is a direct correspondence between the linearity of polypeptide and nucleic acid polymers. In particular, the process of transcription involves the copying of information encoded in a linear polymer of DNA into a linear polymer of RNA. One type of RNA, called messenger RNA, consists of information encoded in a linear polymer that is then read by ribosomes to synthesize the linear polymers that are polypeptides, the latter a process known as translation.


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