Polysaccharides Carbohydrates that starch

Polysaccharides Complex carbohydrates are polysaccharides (most often polymers of glucose), which do not have a sweet taste. Starch is an example of a complex carbohydrate that is found in abundance in plants. Common sources include wheat and other grains, potatoes, dried peas and beans, and vegeta bles. 

The carbohydrates, proteins, and lipids in foods are mostly in complex forms. For example, the carbohydrates are present as disaccharides, such as sucrose, or polysaccharides, such as starch. The first step in digestion is the breakdown of the larger, insoluble molecules into smaller, soluble forms that can be transported across the intestinal wall into the blood for delivery to the tissues. 

CARBOHYDRATES ARE IMPORTANT, naturally occurring organic compounds. They include simple sugars, or monosaccharides, such as glucose and fructose, and polysaccharides, such as starch and cellulose, which are more complex compounds composed of a number of sugar units. Carbohydrates are one of the initial products of photosynthesis. As such, they serve as the molecules that store the sun s energy for later use in metabolism. In addition, carbohydrate polymers are structural materials used by plants and animals. Even our genetic material, DNA, contains carbohydrate units as part of its polymeric backbone. 

Polysaccharides are carbohydrates that can be hydrolyzed to many monosaccharide units. Polysaccharides are naturally occurring polymers (biopolymers) of carbohydrates. They include starch and cellulose, both biopolymers of glucose. Starch is a polysaccharide whose carbohydrate units are easily added to store energy or removed to provide... 

The importance of carbohydrates as energy sources suggests that there is some use for polysaccharides in metabolism. We shall now discuss in more detail some polysaccharides, such as starches, that serve as vehicles for storage of glucose. 

All carbohydrates are polyhydroxyaldehydes, polyhydroxyketones, or molecules that yield polyhydroxy aldehydes or ketones on hydrolysis. Monosaccharides are the smallest carbohydrate molecules and include five- and six-carbon sugars, namely, pentoses and hexoses. Polysaccharides, such as starch and cellulose, lead to many monosaccharides upon hydrolysis. 

Biopolymers are polymers produced by living organisms. They contain monomeric units that are covalently bonded to form macromolecules. There are three main classes of biopolymers, classified according to the monomeric units used and the structure of the biopolymer formed polynucleotides (RNA and DNA), which are long polymers composed of 13 or more nucleotide monomers polypeptides, which are short polymers of amino acids and polysaccharides, which are often linear, bonded, polymeric carbohydrate structures. Polysaccharides include cellulose, starch, gums, glycogen, etc. 

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