What are Carbohydrates?
The Carbohydrates are naturally occurring organic substances. They are present in both plants and animals. The dry mass of plant is composed of 50-80% of the polymeric Carbohydrate cellulose. Carbohydrate is formed in the plants during photosynthesis from Carbon dioxide and water. Animals do not synthesis Carbohydrates but they rely on plants for their supply.
Carbohydrates are mainly compound of Carbon (C), Hydrogen (H) and Oxygen (O). The name “Carbohydrate” arose from the mistaken belief that the substances of this kind were hydrates of Carbon. Details : Chemical formula of Carbohydrates
Physical Properties of Carbohydrates
- In general, Carbohydrates are white solids, sparingly soluble in organic solvents and are soluble in water.
- Many Carbohydrates of low molecular masses have a sweet taste.
- Carbohydrates are often referred to as saccharides (derived from Latin word Saccharum meaning sugar) because of sweet taste of simpler members of the class.
Functions Of Carbohydrates
Carbohydrate functions as a Bio Fuel, a storage food, a framework in body, Anticoagulant, Antigens, and Hormones and provides raw material for industry. Read in Detail : Functions of Carbohydrates.
Types of Carbohydrates
The Carbohydrates are divided into three major classes depending upon whether or not they undergo hydrolysis. They are further divided into Monosaccharides, Oligosaccharides and Polysaccharides.
Monosaccharides are commonly known as simple sugars. They cannot be broken down into more simple sugar with hydrolysis.
Oligosaccharides are complex Carbohydrates which undergo hydrolysis to yield 2 – 10 molecules of Monosaccharides. Oligosaccharides are further divided into Disaccharides, Trisaccharides, Tetrasaccharides and Pentasaccharides depending upon number of Monosaccharides they yield on their hydrolysis.
Polysaccharides are non-sugar complex Carbohydrates which are formed because of interaction of large number of Monosaccharides. These Carbohydrates yield large number of Monosaccharides on hydrolysis.
Examples of Carbohydrates
Glucose is the most important and commonly known carbohydrate which belongs to Monosaccharides class. Other examples of carbohydrates of Monosaccharides class are Galactose, Allose, Altrose, Idose, Gulose and Talose. Monosaccharides are further divided into Aldoses and Ketoses which contain different Carbon atoms. Examples of each type of carbohydrate are given below.
(No. of Carbon Atoms)
Arabinose, Xylose, Lyxose
Gulose, Talose, Idose, Allose, Altrose
Maltose, Lactose and Sucrose are important examples of Oligosaccharides. They have same Chemical formula : C12H22O11 but different structure.
Starch, Glycogen and Cellulose are commonly known Polysaccharides.
Valuable Resources on Web
• Carbohydrate Metabolism
• Chemistry 3B – Lecture 25: Carbohydrates (Part 1)
• Chemistry 3B – Lecture 25: Carbohydrates (Part 2)
• Importance of Carbohydrates
• Chapter 7- Carbohydrates