Question

How are carbohydrates classified? Explain.

Short answer

Short Answer: Carbohydrates are classified into three main types: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are the simplest carbohydrates, consisting of single sugar units like glucose, fructose, and galactose. Disaccharides are formed when two monosaccharides join together, such as sucrose, lactose, and maltose. Polysaccharides are long chains of monosaccharides and can be further classified into homopolysaccharides (composed of a single type of monosaccharide) like starch, glycogen, and cellulose, or heteropolysaccharides (composed of different types of monosaccharide units) like chitin.

Step-by-step solution

1. Introduction to carbohydrates

Carbohydrates are one of the essential nutrients our body needs for energy and proper functioning. They are carbon, hydrogen, and oxygen-containing organic compounds that serve mostly as energy sources and as structural materials in living organisms.

2. Monosaccharides

Monosaccharides are the simplest carbohydrates, consisting of single sugar units. They cannot be hydrolyzed or broken down into smaller carbohydrates. Examples of monosaccharides include glucose, fructose, and galactose. These are usually classified based on the number of carbon atoms they have or their functional group (aldehyde or ketone). Glucose (C6H12O6) is the most common monosaccharide and an essential energy source for our body.

3. Disaccharides

Disaccharides are carbohydrates formed when two monosaccharides are joined together through a condensation reaction, with the elimination of one water molecule. This bond between two sugar molecules is called a glycosidic bond. Examples of disaccharides include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).

4. Polysaccharides

Polysaccharides are long chains of monosaccharides units joined together by glycosidic bonds. Polysaccharides are generally classified into two categories: homopolysaccharides and heteropolysaccharides.

4.1 Homopolysaccharides

Homopolysaccharides are composed of a single type of monosaccharide units. Examples include starch and glycogen, both of which are storage forms of glucose in plants and animals, respectively. Another example is cellulose, which is a structural component found in plant cell walls, composed entirely of glucose units linked together.

4.2 Heteropolysaccharides

Heteropolysaccharides are composed of different types of monosaccharide units. An example of heteropolysaccharide is chitin, which is found in the exoskeletons of arthropods, including insects and crustaceans, and in the cell walls of fungi. Chitin consists of N-acetylglucosamine units linked together by glycosidic bonds.