Lactose

Definition

Lactose is a disaccharide sugar found in milk and dairy products. It is composed of two monosaccharides, glucose and galactose, linked together. Lactose plays an important role in the classification of carbohydrates, the reactions of monosaccharides, and the formation of disaccharides.

5 Must Know Facts For Your Next Test

1. Lactose is the primary carbohydrate found in mammalian milk, providing a source of energy for newborns and infants.
2. The enzyme lactase is responsible for breaking down lactose into glucose and galactose, which can then be absorbed by the body.
3. Some individuals lack sufficient lactase production, leading to lactose intolerance and the inability to properly digest lactose.
4. Lactose can undergo enzymatic hydrolysis to produce glucose and galactose, which are then more readily absorbed and utilized by the body.
5. Lactose is classified as a disaccharide carbohydrate due to its composition of two monosaccharide units, glucose and galactose.

Review Questions

• Explain how the structure of lactose relates to its classification as a disaccharide carbohydrate.
  • Lactose is classified as a disaccharide because it is composed of two monosaccharide units, glucose and galactose, linked together. Disaccharides are carbohydrates that consist of two monosaccharides joined by a glycosidic bond. In the case of lactose, the glucose and galactose molecules are linked in a specific orientation, forming the disaccharide structure. This structural composition is what defines lactose as a disaccharide carbohydrate.
• Describe the role of the enzyme lactase in the digestion and metabolism of lactose.
  • The enzyme lactase is responsible for breaking down lactose into its constituent monosaccharides, glucose and galactose. Lactase catalyzes the hydrolysis of the glycosidic bond between the glucose and galactose units, allowing the body to more easily absorb and metabolize these simpler sugars. Without sufficient lactase production, individuals may experience lactose intolerance, as they are unable to properly digest and utilize the lactose present in dairy products. The activity of lactase is, therefore, crucial for the effective metabolism of lactose and the subsequent utilization of the released glucose and galactose for energy production and other physiological processes.
• Analyze the significance of lactose in the context of carbohydrate classification, monosaccharide reactions, and disaccharide formation.
  • Lactose is a key example that illustrates the interconnectedness of the topics covered in this chapter. As a disaccharide, lactose demonstrates the classification of carbohydrates into monosaccharides and disaccharides. The formation of lactose from the monosaccharides glucose and galactose highlights the reactions of monosaccharides, specifically the condensation reaction that leads to the creation of a disaccharide. Furthermore, the hydrolysis of lactose back into its monosaccharide components showcases the reversibility of these reactions and the importance of understanding the underlying mechanisms. Ultimately, the study of lactose provides a comprehensive understanding of carbohydrate structure, classification, and the dynamic nature of their interconversion through various chemical reactions.

Related terms

Monosaccharide:

The simplest form of carbohydrates, consisting of a single sugar unit. Examples include glucose, fructose, and galactose.

Disaccharide:

A carbohydrate composed of two monosaccharides linked together. Lactose is a disaccharide made up of glucose and galactose.

Hydrolysis:

A chemical reaction that breaks down a compound by the addition of water, often used to break down disaccharides into their monosaccharide components.