A polysaccharide composed solely of glucose units linked by β(l-4) glycosidic bonds. It is the most abundant cell wall and structural polysaccharide in the plant kingdom and probably the most abundant of all compounds found in living organisms. In cell walls it is present in highly organized *microfibrils
, the formation and organization of which is not fully understood at present.
Synthesis of cellulose is thought to take place in the golgi apparatus. Enzymes capable of cellulose formation from primer molecules and nucleotide diphosphate derivatives of glucose (e.g. UDP-and GDP-glucose) have been found in particulate cell fractions arising from the golgi apparatus. Study of cellulose synthetic enzymes has proved difficult because the enzymes are tightly membrane bound.
The enzyme *cellulase
is responsible for the breakdown of cellulose to cellobiose, which is hydrolyzed to its constituent glucose units by the enzyme cellobiase.