Figure 2–49. The hexoses fructose (A) and α- and β-glucose (B), main sources of chemical energy in the cells.
The system ADP⇆ATP is the carrier of chemical energy in these
processes. In the course of catabolic reactions an energy is released and
ADP-molecules can integrate a phosphate group thus forming ATP. When
running reactions are accompanied by energy consumption, the formed
ATP loses its end phosphate group and again is transformed into ADP (Fig.
2–50).
Figure 2–50. The system ADP⇆ATP, carrier of the chemical energy included in them.
Monosaccharides, like proteins and nucleic acids, bind together and
form macromolecules. To a hydroxyl group of one monosaccharide an
aldehyde or keto group of another monosaccharide is joined with removal
of one water molecule. Thus, disaccharides, trisaccharides,
tetrasaccharides, etc. are formed. This process can continue by including
unlimited number of monosaccharides up to obtaining long-chain
polysaccharides containing hundreds or thousands monosaccharide
residues (Fig. 2–51).