What is a disaccharide?

A disaccharide is specifically defined as two monosaccharides bonded together through a glycosidic bond. Monosaccharides are the simplest form of carbohydrates, typically consisting of a single sugar unit, such as glucose or fructose. When two of these simple sugars link together, they form a disaccharide.

Common examples of disaccharides include sucrose (made from glucose and fructose) and lactose (composed of glucose and galactose). This bonding between the two sugar units results in a compound with distinct properties and chemical behavior compared to its individual monosaccharide components.

Understanding disaccharides is essential in biochemistry and nutrition as they play a significant role in various biological processes and serve as important energy sources in the diet. In contrast, a single sugar molecule refers to monosaccharides, while a long chain of sugar units would describe polysaccharides, and a type of protein molecule is unrelated to the definition of carbohydrates altogether.