The simplest examples of carbohydrates are monosaccharides, compounds that each contain a single carbonyl group and two or more hydroxyl groups. Monosaccharides frequently encoutered in biochemistry are sugars that contain from three to seven carbon atoms. Sugars contain one or more chiral centers; the configurations of the possible stereoisomers can be represented by Fischer projection formulas.
What happens if a sugar forms a cyclic molecule?
Sugars exist predominantly as cyclic molecules rather than in an open-chain form. Haworth projection formulas are more realistic representations of the cyclic forms of sugars than are Fischer projection formulas. Many stereoisomers are possible for five and six-carbon sugars, but only a few of the possibilities are encountered frequently in nature.
What are some oxidation-reduction reactions of sugars?
Monosaccharides can undergo various reactions. Oxidation reactions make up on important group.
What are some important esterification reactions of sugars?
Esterification of sugars to phophoric acid plays an important role in metabolism.
What are glycosides, and how do they form?
The most important reaction of sugars by far is the formation of glycosidic linkages, which give rise to oligosaccharides and polysaccharides.
What are some other important derivatives of sugars?
Three important examples of oligosaccharides are the disaccharides sucrose, lactose, and maltose. Sucrose is common table sugar.
Are any other disaccharides important to us?
Lactose occurs in milk, and maltose is obtained via the hydrolysis of starch.
How do cellulose and starch differ from one another?
In polysaccharides, the repeating unit of the polymer is frequently limited to one or two kinds of monomer. Cellulose and starch differ in the anomeric form of their glycosidic bonds: the alpha form in starch and the beta form in cellulose.
Is there more than one form of starch?
Starch exists in two polymeric forms, the linear amylose and the branched amylopectin.
How is glycogen related to starch?
Starch, found in plants, and glycogen, which occurs in animals, differ from each other in the degree of branching in the polymer structure.