Lactose

Definition

Lactose is a disaccharide sugar composed of two monosaccharides, glucose and galactose, and is primarily found in milk and dairy products. It plays a vital role as an energy source, especially for infants, and is important for understanding how carbohydrates function within biological systems. The ability to digest lactose depends on the presence of the enzyme lactase, which breaks down lactose into its constituent sugars.

5 Must Know Facts For Your Next Test

1. Lactose intolerance occurs when the body does not produce enough lactase, leading to difficulty digesting dairy products.
2. Lactose is often referred to as milk sugar because it is the primary sugar found in mammalian milk.
3. In addition to being a source of energy, lactose also plays a role in the absorption of certain minerals, such as calcium and magnesium.
4. Fermentation of lactose by bacteria in the gut can lead to gas production, which is often associated with discomfort in lactose-intolerant individuals.
5. Some dairy products, like yogurt and hard cheeses, contain lower levels of lactose compared to milk, making them easier to digest for those with lactose intolerance.

Review Questions

• How does the presence or absence of lactase affect an individual's ability to digest lactose?
  • The presence of lactase is crucial for digesting lactose effectively. When lactase is produced in sufficient quantities, it breaks down lactose into glucose and galactose, which can then be absorbed into the bloodstream. In individuals lacking adequate lactase production, lactose remains undigested in the gut, leading to symptoms of lactose intolerance such as bloating and gas due to fermentation by gut bacteria.
• Discuss the implications of lactose intolerance on dietary choices and nutrition.
  • Lactose intolerance significantly impacts dietary choices as individuals may need to limit or avoid dairy products to prevent discomfort. This can lead to nutritional challenges, particularly regarding calcium intake, since dairy is a primary source of this mineral. To address these challenges, many people turn to lactose-free alternatives or seek other sources of calcium such as leafy greens, fortified plant-based milks, or supplements.
• Evaluate the biological significance of lactose as an energy source in early human development and its relationship with lactase persistence.
  • Lactose serves as an essential energy source for infants who rely on breast milk during early development. The presence of lactase allows them to efficiently metabolize this sugar for growth and energy. In some populations, genetic adaptations have led to lactase persistence into adulthood, enabling continued consumption of dairy products without adverse effects. This adaptation highlights the interplay between diet, genetics, and survival strategies in human evolution.

Related terms

Lactase: An enzyme produced in the small intestine that is responsible for breaking down lactose into glucose and galactose.

Galactose: A monosaccharide that, along with glucose, makes up lactose; it is essential for various metabolic processes in the body.

Disaccharide: A type of carbohydrate formed from two monosaccharides; examples include sucrose, maltose, and lactose.