Question

Sucrose is cleaved in your saliva by the enzyme sucrase to release glucose and fructose. Use the structural formula of sucrose to describe fructose using the terms that define its carbon number and placement of the carbonyl group.

Short answer

Fructose can be described as a ketohexose sugar, meaning it has six carbons (hexose sugar) and a ketone carbonyl group located at the second carbon atom.

Step-by-step solution

Understanding the structure of sucrose

Sucrose is a disaccharide composed of two monosaccharides: glucose and fructose. They are linked together by a glycosidic bond between their anomeric carbons.

Recognizing the breakdown of sucrose into glucose and fructose

The enzyme sucrase present in saliva breaks down sucrose by cleaving the glycosidic bond between glucose and fructose. This releases one molecule each of glucose and fructose.

Identifying the carbon number of fructose

Fructose is a monosaccharide with a total of six carbons. It is also known as a hexose sugar.

Identifying the placement of the carbonyl group in fructose

In fructose, the carbonyl group is present at the second carbon atom. Therefore, fructose is classified as a ketohexose sugar.

Describing fructose using the terms defining its carbon number and placement of the carbonyl group

Fructose can be described as a ketohexose sugar, meaning it is a hexose sugar (having six carbons) with a ketone carbonyl group located at the second carbon atom.

Key concepts

Disaccharides Breakdown

Understanding the process of disaccharides breakdown is crucial in the field of biochemistry. Disaccharides, like sucrose, consist of two monosaccharides linked together. During digestion, specific enzymes, such as sucrase, facilitate the breakdown of these disaccharides.

The function of sucrase is to cleave the glycosidic bond that holds the two sugar molecules together. When you consume something sweet containing sucrose, the enzyme sucrase in your saliva catalyzes the hydrolysis of sucrose, resulting in the release of its constituent monosaccharides, glucose and fructose. This is an essential process that allows your body to utilize the sugars for energy.

Furthermore, understanding this biochemical reaction has practical applications. For example, individuals with sucrase deficiency may experience discomfort after consuming sugary foods, leading to a condition known as sucrose intolerance.

Monosaccharides

Monosaccharides are the simplest form of carbohydrates and act as the building blocks for more complex sugars. They consist of a single sugar molecule and serve as a vital energy source for the body. Glucose and fructose, for instance, are common monosaccharides resulting from the enzymatic breakdown of disaccharides like sucrose.

Both glucose and fructose have six carbon atoms, but they differ in the placement of their carbonyl group. This positional difference is what distinguishes glucose as an aldohexose and fructose as a ketohexose. Students should grasp the significance of these differences as they affect the sugar's properties and its role in metabolism.

Glycosidic Bond

The glycosidic bond is a covalent link that connects two sugar molecules in oligosaccharides and polysaccharides. In the case of sucrose, a disaccharide, the glycosidic bond forms between the anomeric carbon of one monosaccharide and a hydroxyl group on the other.

Understanding the nature of the glycosidic bond is vital because its position and type determine the properties of the sugar compound and how the bond can be broken down. Enzymes like sucrase are specialized to cleave specific glycosidic bonds, a necessary step for the absorption and metabolization of dietary sugars.

Ketohexose

Ketohexose refers to a monosaccharide that contains six carbon atoms, with a ketone carbonyl group positioned at the second carbon atom. Fructose, which is released upon the breakdown of sucrose by the enzyme sucrase, is a prime example of a ketohexose.

The placement of its carbonyl group endows fructose with distinct chemical and physical properties compared to glucose, an aldohexose, where the carbonyl group is at the first carbon. This difference in structure plays a critical role in how these sugars interact with other biological molecules and enzymes. When optimizing the understanding of how sugars function in the body, the classification of sugars like fructose as a ketohexose helps clarify its role in metabolism and its impact on health.