Ágar e Agarose

Agar (pronounced /ˈɑːɡər/, "ah-gər") or agar-agar (/ˈɑːɡərˈɑːɡər/, "ah-gər-ah-gər") is a gelatinous substance, obtained from algae and discovered in 1658 by Minora Tanzaemon in Japan, where it is called Kanten, and is used traditionally in some confectionaries.

Agar is derived from the polysaccharide agarose, which forms the supporting structure in the cell walls of certain species of algae, and which is released on boiling. These algae are known as agarophytes and belong to the Rhodophyta (red algae) phylum .^[1][2] Agar is actually the resulting mixture of two components: the linear polysaccharide agarose, and a heterogeneous mixture of smaller molecules called agaropectin.^[3]

Throughout history into modern times, agar has been chiefly used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture medium for microbiological work. Agar (agar-agar) can be used as a laxative, an appetite suppressant, vegetarian gelatinsubstitute, a thickener for soups, in fruit preserves, ice cream, and other desserts, as a clarifying agent in brewing, and for sizing paper and fabrics.^[4]

An agarose is a polysaccharide polymer material, generally extracted from seaweed. Agarose is a linear polymer made up of the repeating unit of agarobiose, which is a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose.^[1] Agarose is one of the two principal components ofagar, and is purified from agar by removing agar's other component, agaropectin.^[2]

Agarose is frequently used in molecular biology for the separation of large molecules, especially DNA, by electrophoresis. Slabs of agarose gels (usually 0.7 - 2%) for electrophoresis are readily prepared by pouring the warm, liquid solution into a mold. A wide range of different agaroses, of varying molecular weights and properties are commercially available for this purpose.