Carbohydrates are polyhydroxy aldehydes or ketones, or compounds that produce them on hydrolysis. The term sugar is applied to carbohydrates soluble in water and sweet to taste. Carbohydrates are the major dietary energy sources, besides their involvement in cell structure and various other functions.
Carbohydrates are broadly classified into 3 groups—monosaccharides, oligosaccharides, and polysaccharides. The monosaccharides are further divided into different categories based on the presence of functional groups (aldoses or ketoses) and the number of carbon atoms (trioses, tetroses, pentoses, hexoses, and heptoses).
Functions of carbohydrates
Carbohydrates participate in a wide range of functions
1. They are the most abundant dietary source of energy (4Cal/g) for all organisms.
2. Carbohydrates are precursors for many organic compounds (fats, amino acids).
3. Carbohydrates (as glycoproteins and glycolipids) participate in the structure of cell membrane and cellular functions such as cell growth, adhesion, and fertilization.
4. They are structural components of many organisms. These include the fiber (cellulose) of plants, the exoskeleton of some insects, and the cell wall of microorganisms.
5. Carbohydrates also serve as the storage form of energy (glycogen) to meet the immediate energy demands of the body.
If two monosaccharides differ from each other in their configuration around a single specific carbon (other than anomeric) atom, they are referred to as epimers to each other.
Enantiomers are a special type of stereoisomers that are mirror images of each other.
The process of shifting a hydrogen atom from one carbon atom to another to produce enediols is known as tautomerization.
Mutarotation is defined as the change in the specific optical rotation representing the interconversion of α and β forms of D-glucose to an equilibrium mixture.(more…)