Cellobiose: Definition, Functions, Formation, Decomposition and Examples of this Type of Disaccharide

It is made up of two glucose molecules, but they are linked in a different way.

Cellobiose is a type of disaccharide. Is that the cellulose made, the main component of the cell walls of plants, is hydrolyzed.

Cellobiose is used in bacteriology , the study of bacteria, to perform chemical analysis.

A disaccharide, also called a double sugar, is a molecule made up of two monosaccharides or simple sugars. Three common disaccharides are sucrose, maltose, and lactose. They have 12 carbon atoms, and their chemical formula is C  12  H  22  O  11 .

Other less common disaccharides include, apart from cellobiose, lactulose and trehalose. Disaccharides are formed by dehydration reactions in which a total of one molecule of water is removed from the two monosaccharides.

Disaccharide functions

Disaccharides are carbohydrates found in many foods and are often added as sweeteners. Sucrose, for example, is table sugar, and it is the most common disaccharide that humans eat.

It is also found in other foods such as beets. When disaccharides like sucrose are digested, they break down into simple sugars and are used for energy. Lactose is found in breast milk and provides nutrition for babies.

Maltose is a sweetener often found in chocolates and other sweets.

Plants store energy in the form of disaccharides such as sucrose and it is also used to transport nutrients in the phloem. As it is a source of energy storage, many plants, such as sugar cane, are high in sucrose.

Trehalose is used for transport in some algae and fungi. Plants also store energy in polysaccharides, which are many monosaccharides attached. Starch is the most common polysaccharide used for storage in plants, and it breaks down into maltose.

Plants also use disaccharides to transport monosaccharides like glucose, fructose, and galactose between cells. The packaging of monosaccharides into disaccharides makes the molecules less likely to break down during transport.

Formation and decomposition of disaccharides

When disaccharides are formed from monosaccharides, an -OH (hydroxyl) group is removed from one molecule and an H (hydrogen) is removed from the other.

Glycosidic bonds are formed to bind to molecules; These are covalent bonds between a carbohydrate molecule and another group (which does not necessarily have to be another carbohydrate). The H and -OH that were removed from the two monosaccharides join to form a molecule of water, H  2  O.

For this reason, the process of forming a disaccharide from two monosaccharides is called a dehydration reaction or a condensation reaction.

When disaccharides are broken down into their monosaccharide components by enzymes, a water molecule is added. This process is called hydrolysis. It should not be confused with the dissolving process, which occurs when sugar dissolves in water, for example.

The sugar molecules themselves do not change their structure when they dissolve. Solid sugar simply turns into a liquid and becomes a solute or a dissolved component of a solution.

Other examples of disaccharides


Sucrose, commonly known as table sugar in its refined form, is a disaccharide found in many plants. It is composed of the monosaccharides glucose and fructose. In the form of sugar, sucrose is a very important component of the human diet as a sweetener.

Sugar was first extracted and purified from sugar cane in India and in the 8  th  century BC. In fact, the word sweet gets its name in part from the word  khanda  , which was a name for sugar crystals in Sanskrit. Today, about 175 metric tons of sugar are produced each year.

People with congenital sucrase-isomaltase deficiency (CSID) are intolerant to sucrose and cannot digest it well because they lack the enzyme sucrose-isomaltase. Some people with CSID also have trouble digesting starches.

A person who is sucrose intolerant should limit sucrose as much as possible, and may need to take supplements or medications.


Maltose, also known as malt sugar, is formed from two glucose molecules. Malt is formed when grains soften and grow in water, and is a component of beer, starchy foods such as cereal, pasta, and potatoes, and many sweetened processed foods.

In plants, maltose is formed when starch breaks down for food. It is used by germinating seeds to grow.


Lactose, or milk sugar, is made up of galactose and glucose. Mammalian milk is rich in lactose and provides nutrients for babies. Most mammals can only digest lactose as babies and lose this ability as they mature.

In fact, humans who are able to digest dairy products in adulthood actually have a mutation that allows them to do so.

This is the reason why many people are lactose intolerant; Humans, like other mammals, did not have the ability to digest lactose after infancy until this mutation prevailed in certain populations about 10,000 years ago.

Currently, the number of people with lactose intolerance varies widely from one population to another, from <10% in Northern Europe to 95% in some parts of Africa and Asia. The traditional diets of different cultures reflect this in the amount of dairy products that are consumed.