Learning Outcomes
i. Define monosaccharides.
ii. Classify monosaccharides into aldoses and ketoses.
iii. Describe the structure and function of different types of monosaccharides.
i. What are monosaccharides?
Monosaccharides are the simplest form of carbohydrates. They are made up of a single sugar unit. Monosaccharides have the empirical formula (CH2O)n, where n is the number of carbon atoms in the molecule. The most common monosaccharides have three to seven carbon atoms.
Monosaccharides are classified into two groups based on the placement of the carbonyl group: aldoses and ketoses. Aldoses have the carbonyl group at the first carbon atom, while ketoses have the carbonyl group at the second carbon atom.
Aldoses and ketoses
The following table shows the most common monosaccharides and their classification as aldoses or ketoses:
| Monosaccharide | Classification |
|---|---|---|
| Glucose | Aldohexose |
| Fructose | Ketohexose |
| Galactose | Aldohexose |
| Ribose | Aldopentose |
| Deoxyribose | Aldopentose |
ii. Structure and function of monosaccharides
Monosaccharides are the basic building blocks of carbohydrates. They are the simplest form of carbohydrates and can be used directly by cells for energy. Monosaccharides are also used to synthesize other types of carbohydrates, such as disaccharides and polysaccharides.
Glucose is the most common monosaccharide and is the main source of energy for most organisms. Glucose is stored in the liver and muscles as glycogen, which can be broken down into glucose to provide energy when needed.
Fructose is a monosaccharide that is found in fruits and vegetables. Fructose is sweeter than glucose and is often used as a sweetener in foods and beverages.Galactose is a monosaccharide that is found in milk and other dairy products. Galactose is used to synthesize lactose, which is the disaccharide that is found in milk.
Ribose and deoxyribose are monosaccharides that are found in ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), respectively. RNA and DNA are the molecules that store and transmit genetic information.
Real-world applications of monosaccharides
Monosaccharides are used in a variety of products and industries. For example, glucose is used in intravenous fluids and in the production of biofuels. Fructose is used as a sweetener in foods and beverages. Galactose is used in infant formula and in the production of lactose-free dairy products. Ribose and deoxyribose are used in the production of vaccines and other pharmaceuticals
Monosaccharides are the simplest form of carbohydrates. They are essential nutrients for most organisms and are used to provide energy, synthesize other types of carbohydrates, and store genetic information.
