Carbohydrates

Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy (e.g., starch, glycogen) and structural components (e.g., cellulose in plants and chitin in animals). In addition, carbohydrates and their derivatives play major roles in the working process of the immune system, fertilization, pathogenesis, blood clotting, and development.

Carbohydrates make up most of the organic matter on Earth because of their extensive roles in all forms of life.

1. Carbohydrates serve as energy stores, fuels, and metabolic intermediates.
   
2. Ribose and deoxyribose sugars form part of the structural framework of RNA and DNA.
   
3. Polysaccharides are structural elements in the cell walls of bacteria and plants. In fact, cellulose, the main constituent of plant cell walls, is one of the most abundant organic compounds in the biosphere.
4. Carrbohydrates are linked to many proteins and lipids, where they play key roles in mediating interactions between cells and interactions between cells and other elements in the cellular environment.