component of the cell walls of some microorganisms. It is a homopolymer
of N-acetyl-D-glucosamine. Both cellulose and chitin are insoluble in water.
Starch and glycogen are the basic reserve polysaccharides. Starch is
met in two forms — α-amylose and amylopectin.
Corn-bean plants, potatoes, etc. are especially rich in starch. Under the
action of enzymes starch decomposes to glucose, which is utilized in
metabolism. Glycogen is a reserve polysaccharide in the animal tissues and
organs. In larger quantities it is accumulated in the liver and muscles. It is easily
hydrolized by α- and β-amylase with decomposing to glucose and maltose.
Except with each other, carbohydrates form stable bonds with proteins,
nucleic acids, lipids, etc. Thus formed compounds, especially glycoproteins,
nucleosides and glycolipids, perform important biological functions.
All stated in Section 2. 7 gives only an idea about the structural
organization and importance of proteins, nucleic acids and carbohydrates
considered to be basic building blocks of the living systems. It does not
have for an object to exhaust them as problems from chemical and
biochemical point of view, since this is a huge subject, discussed in detail in
the special literature. Possibly, in the course of time some current views on
their role and importance will alter.
Noteworthy is the fact, that by forming the biopolymers —
polypeptides, polynucleotides and polysaccharides — the binding of single
monomers is accompanied by a removal of one water molecule (H₂O). The
mechanism is extremely similar (Fig. 2–52). A question arises: why these
processes are so similar and for what reason only H₂O is removed in them,
and whether it had been a matrix for their formation? Let hope that in near
future quantum physics and chemistry will answer this question, which will
throw light upon the general principles of organization of the living matter.