Reality → Life → Biochem → Carbohydrates
All carbohydrates (also called saccharides) consist of carbon, hydrogen, and oxygen according to the general chemical formula Cm(H2O)n [1] . The compounds range from simple sugars (monosaccharides) to complex substances (polysaccharides) such as starch and cellulose. They are important energy reservoirs of practically all plants and animals. Under the catalytic effect of enzymes, polysaccharides can be broken down by hydrolysis [2] into oligosaccharides, disaccharides, and monosaccharides. Carbohydrates participate in complex biochemical reactions inside cells to generate, store, and transfer energy needed to sustain life. The most common and important carbohydrates include:
Hydrolysis is a reaction with water that can break down long molecular chains of equal units (polymers such as polysaccharides) into smaller segments, whereby the H cations bond with one reaction product and the OH anions with another reaction product (see Ions). The reaction normally requires catalysis.
In the glucose molecule the carbonyl group (>C=O) occupies an end-position of the 6-carbon chain, whereas in the fructose molecule it occupies the second C-position. This change explains lower reactivity of the fructose molecule and reduced capacity for polymerization.
Cellulose builds the cell walls of plants (and also of fungi and prokaryotes). It is the major component of wood, which consists of cellulosic fibers surrounded and impregnated by lignin, a hardening polymeric substance. Cellulose is the most abundant organic substance on Earth.
Adenosine Tri-Phosphate (ATP, chemical formula C10H16N5O13P3) is composed of ribose, adenine (a cyclic nitrogen-based organic compound), and 3 phosphate groups. ATP plays a major role in the energy transfers of metabolism and the production of proteins. ATP is constantly used and generated in all organisms. The human body contains about 250 grams ATP but turns over about 75 kg per day, equivalent to a daily ATP stock renewal rate of 300, or one renewal every 5 minutes.