Agar is made up of two polysaccharides, agaropectin and agarose.
As with carageenan
the backbone of these polysaccharides is the sugar
Agar is most familiar as the gelatinous growth medium used in petri dishes
to culture bacteria. But it also finds uses in cooking as a gel for
jellies and fillings. It is a soluble fiber, and as such finds uses
as a laxative and diet aid.
As a growth medium, agar has nice properties, such as a high melting
point (85 degrees Celsius), and a lower solidifying point (40 degrees).
It can stay gelled at incubating temperatures.
Purified agarose is used as a medium for electrophoresis, the separation
of proteins or DNA fragments by size using an electric field.