Starch, biological function

Several alkenes occur naturally in living organisms. Some of these alkenes act as hormones and control biological functions. Plants produce ethene as a hormone to stimulate flower and seed production and to ripen fruits. Ethene stimulates enzymes in the plants to convert starch and acids of unripe fruit into sugars. The enzymes also soften fruit by breaking down pectin in cell walls. 

Biologically, carbohydrates are most important as energy sources. This is especially true for monosaccharides, disaccharides, and starches. Starches also function as energy storage molecules in plants. Cellulose is an essential component of plant cell walls. 

Starch Biology, Structure and Functionality A. Huber W. Praznik... 

In both their industrial and biological functions, the 3-dimensional characteristics of carbohydrates are important. Many of these stereochemical features are described for carbohydrates in the classic text by Stoddart (2). The inqportance of stereochemistry is underscored by the unique chemical and physical properties of the individual sugars, many of which are configurational isomers. Stereochemistry also plays a role in detentlining the properties of polysaccharides. Molecular shape is as significant for the properties of an industrially modified starch as it is for the recognition of one particular blood type and the rejection of others. 

Biological Functions of Oligosaccharides and Polysaccharides. Polysaccharides serve two important biological roles. Glycogen and starch are polymers of glucose units linked in a(l —> 4) linkages that serve as carbohydrate reserves for animals, bacteria, and plants. Because these polymers are readily converted to intermediates for pathways that yield metabolic energy, they can also be... 

Caspar, T. 1994. Genetic dissection of the biosynthesis, degradation and biological functions of starch. In "Arabidopsis (Monograph 27) (E. M. Meyerowitz and C. Sommerville, eds.). pp. 913-936. Cold Spring Harbor Lab. Press, Coldspring Harbor, New York. 

Volume therapy with etherified starches in trauma patients results in a reduction in circulating adhesion molecules, an effect that is not observed with albumin infusion (51). Continuous infusion of pentoxifylline did not have a beneficial modulating action on circulating adhesion molecules. Adhesion molecules appear to play an important role in tissue damage secondary to the inflammatory process. Besides neutrophil- and endothelium-bound adhesion molecules, soluble forms have been detected in the circulating blood in trauma patients. They seem to be markers of endothelial damage, but they may also have other biological functions. 

Saccharides are present in food raw materials in quantities ranging from about 1% in meats and fish, to about 4.5% in milk, 18% in potatoes, and 15-20% in sugar beets, to about 70% in cereal grains. Polysaccharides participate in the formation of structures in plants. They are also stored in plants as starch and in muscles as glycogen. Other saccharides are dissolved in tissue fluids or perform different biological functions in free nucleotides, as components of nucleic acids, or bound to proteins and lipids. 

Polysaccharides, i.e., linear or branched heteropolymers of sugars and derived components several are polyelectrolytes. The degree of polymerization is mostly 103 to 104. The main biological functions are nutritional (primarily starch in plants, glycogen in animals) and building material (in plants). The latter are called structural polysaccharides, which occur in a great variety of types and mostly form mixed and highly complex structures, especially in cell walls. 

Carbohydrates, also referred to as saccharides, are polyhydroxyaldehydes or polyhydroxyketones or compounds that can be hydrolyzed to or derived from polyhydroxyaldehydes or polyhydroxyketones. Carbohydrates have many important biological functions— to store and generate energy in animals and plants (glucose, starch, glycogen), as supportive structures in plants (cellulose) and crustaceans (chitin), and as components of cell membranes and nucleic acids. 

Looking at the biological function, the primary extractives are necessary for maintaining the metabolism and supply of the components for the biosynthesis of the secondary substances. Typical primary substances include carbohydrates (sugars), which can be found for example as monosaccharides, disaccharides and as starch as well as fats and proteins. As sapwood is responsible for the constant water and nutrient supply of the whole tree, mainly primary extractives are involved, which are also used by various micro-organisms as a source of food. 

Polysaccharides, or complex carbohydrates, are large molecules, having molar masses between 4000 and 150,000,000 g/mol. You will study three polysaccharides with greatly different biological functions—cellulose, starch, and glycogen. They share a common monomer glucose. 

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