Disaccharides

Definition

Disaccharides are a class of carbohydrates composed of two monosaccharide units joined together by a covalent bond. They serve as important energy sources and building blocks for larger carbohydrate structures in living organisms.

5 Must Know Facts For Your Next Test

1. The three most common disaccharides are sucrose, lactose, and maltose, which are found in a variety of foods and play crucial roles in metabolism.
2. Disaccharides are formed when two monosaccharides, such as glucose and fructose, or glucose and galactose, are joined together through a process called dehydration synthesis.
3. Disaccharides can be broken down into their constituent monosaccharides through hydrolysis, a process that releases energy and provides the body with readily available carbohydrates.
4. Sucrose, also known as table sugar, is composed of one glucose and one fructose unit and is a common sweetener found in many foods and beverages.
5. Lactose, the disaccharide found in milk, is composed of one glucose and one galactose unit and is essential for the growth and development of infants and young children.

Review Questions

• Explain the process of dehydration synthesis in the formation of disaccharides.
  • Dehydration synthesis is the chemical reaction that occurs when two monosaccharide units, such as glucose and fructose, are joined together to form a disaccharide. During this process, a water molecule is removed, and the two monosaccharides are covalently bonded through a glycosidic bond. This reaction results in the formation of a larger, more complex carbohydrate molecule that can be used as an energy source or building block for larger carbohydrate structures in the body.
• Describe the role of disaccharides in metabolism and energy production.
  • Disaccharides play a crucial role in metabolism and energy production. Once consumed, disaccharides can be broken down through hydrolysis into their constituent monosaccharides, such as glucose and fructose. These monosaccharides can then be absorbed and transported throughout the body, where they can be used as a readily available source of energy for cellular processes, or stored for later use in the form of glycogen. The breakdown of disaccharides also releases energy that can be used to power various metabolic pathways, making them an essential component of the body's energy production and regulation.
• Analyze the differences between the three most common disaccharides (sucrose, lactose, and maltose) and their significance in the human diet.
  • The three most common disaccharides, sucrose, lactose, and maltose, differ in their monosaccharide composition and have distinct roles in the human diet. Sucrose, composed of glucose and fructose, is a common sweetener found in many processed foods and beverages. Lactose, made up of glucose and galactose, is the primary carbohydrate in milk and is essential for the growth and development of infants and young children. Maltose, consisting of two glucose units, is produced during the digestion of starch and is commonly found in germinating grains, such as barley, which is used in the production of beer and other malt-based products. The differences in these disaccharides' structures and sources lead to variations in their metabolic processing, nutritional value, and overall significance in the human diet.

Related terms

Monosaccharides:

The simplest form of carbohydrates, consisting of a single sugar unit that cannot be broken down into smaller sugar molecules.

Polysaccharides:

Large carbohydrate molecules composed of many monosaccharide units linked together, such as starch, glycogen, and cellulose.

Glycosidic Bond:

The covalent bond that connects two monosaccharide units to form a disaccharide or polysaccharide.