Question

Complete the following word equation: $$\text { Lactose }+\mathrm{H}_{2} \mathrm{O} \longrightarrow ?+?$$ Where in the digestive system does this process occur?

Short answer

Lactose + H₂O → Glucose + Galactose. This process occurs in the small intestine.

Step-by-step solution

Understand the Reaction

Lactose is a disaccharide sugar found in milk. When lactose interacts with water (hydrolysis), it is broken down into its component sugars. This reaction is facilitated by the enzyme lactase.

Identify the Products

When lactose undergoes hydrolysis, it splits into two monosaccharides: glucose and galactose. Therefore, the word equation becomes: Lactose + H₂O → Glucose + Galactose.

Determine the Location in the Digestive System

The hydrolysis of lactose occurs in the small intestine. Lactase, the enzyme required for this reaction, is present in the lining of the small intestine.

Key concepts

Disaccharide

Lactose is an example of a disaccharide, which is a type of sugar composed of two monosaccharide molecules linked together. In simpler terms, you can think of disaccharides as a pair of sugar units joined to make a larger sugar. Other common disaccharides found in our diet include sucrose, commonly known as table sugar, and maltose, found in malted foods.

• Each disaccharide is formed when two monosaccharides undergo a condensation reaction, where a molecule of water is removed.
• To break down a disaccharide back into monosaccharides, a water molecule is added in a process called hydrolysis.

Understanding disaccharides is key in nutrition as they provide energy upon digestion. They must be broken down by our digestive system before their energy can be used by the body.

Monosaccharides

Monosaccharides are the simplest form of carbohydrates, often referred to as simple sugars. Each monosaccharide molecule typically consists of a single sugar unit, and they serve as building blocks for more complex carbohydrates, such as disaccharides and polysaccharides.

• Common examples include glucose, fructose, and galactose.
• These sugars are readily absorbed by the body and used for energy, making them crucial for maintaining bodily functions.

In the context of lactose hydrolysis, the disaccharide lactose is split into two monosaccharides: glucose and galactose. This is an important process, as it allows the nutrients to be absorbed efficiently into the bloodstream to provide energy for cells.

Small Intestine Digestion

The process of digesting lactose primarily takes place in the small intestine, a part of the digestive system that plays a critical role in nutrition absorption. The small intestine is equipped with various enzymes that aid in breaking down food molecules into simpler compounds.

• Lactase is the specific enzyme present in the small intestinal lining that catalyzes the hydrolysis of lactose.
• Once lactose is converted into glucose and galactose, these substances can then be absorbed through the intestinal wall and into the bloodstream.

Efficient digestion in the small intestine is vital for proper nutrition, as this is where the majority of nutrient absorption occurs. It's important to note that individuals who are lactose intolerant have a deficiency in lactase, leading to undigested lactose remaining in the digestive system, which can cause discomfort.