Understanding Biomolecules: Carbohydrates and Their Functions

Understanding Biomolecules

Biomolecules are organic compounds that perform essential functions within cells. These include carbohydrates, lipids, amino acids, and proteins. From the perspective of organic chemistry, we analyze their chemical structure and functional groups, distinct from their biological roles.

Carbohydrates: Definition and Structure

Carbohydrates, also known as saccharides, are polyfunctional oxygenated compounds containing either aldehyde or ketone groups. Because they possess multiple hydroxyl groups, they are classified as polyhydroxylated. Many low-molecular-weight carbohydrates are referred to as sugars due to their sweet taste.

Classification of Monosaccharides

Monosaccharides are simple molecules containing between 3 and 7 carbon atoms. The most common are pentoses (5 carbons) and hexoses (6 carbons). Glucose is the most significant monosaccharide, as its oxidation provides the energy required for various cellular processes.

Glucose Structure

Glucose is classified as a hexose and an aldose. Its structure involves a carbon chain with an aldehyde functional group and multiple hydroxyl groups.

Classification by Hydrolysis

Carbohydrates are classified based on their ability to be hydrolyzed:

• Monosaccharides: Cannot be hydrolyzed into simpler sugars.
• Disaccharides: Formed by the union of two monosaccharides.
• Trisaccharides: Formed by the union of three monosaccharides.
• Polysaccharides: Macromolecules formed by a large number of monosaccharides.

Common Disaccharides

• Sucrose (Cane sugar): Formed by glucose and fructose.
• Lactose (Milk sugar): Composed of galactose and glucose.
• Maltose (Malt sugar): Composed of two glucose molecules.

Key Polysaccharides

• Cellulose: Provides structural support for plants (found in wood and fibers).
• Starch: The energy reserve for plants, stored in stems, roots, and seeds (found in bread, cereals, and flours).
• Glycogen: The energy reserve for animals and humans, stored in the liver and muscles, which decomposes to release glucose when the body requires energy.