Which two monosaccharides are found in sucrose table sugar? An In-Depth Look at Glucose and Fructose

December 17, 2025 •

2 min read

Sucrose, the scientific term for table sugar, is a disaccharide, meaning it is composed of two smaller, simpler sugar units, or monosaccharides. This fundamental knowledge helps us understand not only the makeup of sugar, but also how our bodies process this common sweetener, revealing which two monosaccharides are found in sucrose table sugar.

Quick Summary

Sucrose is a disaccharide composed of one glucose molecule and one fructose molecule, joined by a glycosidic bond. During digestion, an enzyme called sucrase breaks this bond through hydrolysis, separating sucrose into its two monosaccharides, glucose and fructose, for absorption. These simple sugars are then used by the body for energy.

Key Points

Sucrose Composition: Table sugar, or sucrose, is a disaccharide made from two monosaccharides: glucose and fructose.
Dehydration Synthesis: Sucrose is formed when a molecule of glucose and a molecule of fructose join together, releasing a water molecule in the process.
Glycosidic Bond: The two monosaccharides are linked by a covalent bond known as a 1,2-glycosidic linkage.
Digestion with Sucrase: The body uses the enzyme sucrase in the small intestine to break the glycosidic bond through hydrolysis, separating sucrose back into glucose and fructose for absorption.
Distinct Metabolism: Once separated, glucose and fructose are metabolized differently; glucose is used for immediate energy, while fructose is processed by the liver.
Source vs. Added Sugar: The health impacts of glucose and fructose differ between naturally occurring sugars in whole foods (like fruit) and added sugars in processed products.

The Monosaccharide Building Blocks of Sucrose

Sucrose is a disaccharide, a type of carbohydrate formed from two linked monosaccharides. The two monosaccharides that form sucrose are glucose and fructose.

Glucose: The Body's Primary Energy Source

Glucose is a monosaccharide often called 'blood sugar' and is a primary energy source. It has a six-membered ring structure (pyranose) in its ring form. Digested glucose enters the bloodstream and is used for energy or stored.

Fructose: 'Fruit Sugar'

Fructose is a monosaccharide found in fruits, vegetables, and honey. It has a five-membered ring structure (furanose) within sucrose. Fructose is sweeter than glucose and is primarily processed by the liver.

The Condensation Reaction that Forms Sucrose

Sucrose is formed from glucose and fructose through a condensation reaction, which releases a water molecule and creates a glycosidic bond. Specifically, an alpha-glucose and a beta-fructose molecule join, removing a hydroxyl group and a hydrogen atom to form water. This forms a 1,2-glycosidic linkage.

Digestion: Breaking Down Sucrose

Digestion breaks the glycosidic bond in sucrose through hydrolysis, the reverse of the condensation reaction. The enzyme sucrase in the small intestine catalyzes this process by adding a water molecule, splitting sucrose into glucose and fructose. These monosaccharides are then absorbed into the bloodstream.

A Comparison of Common Disaccharides

Understanding other disaccharides helps highlight sucrose's unique structure.


Feature	Sucrose (Table Sugar)	Lactose (Milk Sugar)	Maltose (Malt Sugar)
Monosaccharide Units	Glucose + Fructose	Glucose + Galactose	Glucose + Glucose
Glycosidic Bond	$\alpha$-1,2	$\beta$-1,4	$\alpha$-1,4
Primary Source	Sugar cane, sugar beets	Dairy products	Grains (e.g., barley)
Enzyme for Digestion	Sucrase	Lactase	Maltase

Health Implications of Glucose vs. Fructose

Glucose and fructose have different metabolic effects. Glucose metabolism is insulin-regulated, while fructose is mainly processed in the liver without the same insulin response. High consumption of added fructose may be linked to health issues, but fructose in whole fruits is different due to fiber and other nutrients. Learn more about different sugars from Harvard Health Publishing.(https://www.health.harvard.edu/blog/are-certain-types-of-sugars-healthier-than-others-2019052916699)

Conclusion: The Final Word on Sucrose

Sucrose table sugar is composed of the monosaccharides glucose and fructose, linked by a chemical bond. Digestion breaks this bond, allowing the body to use glucose and fructose for energy. Their distinct metabolic pathways are a key factor in the health effects of dietary sugar.

Frequently Asked Questions

Sucrose is the scientific name for table sugar. It is a disaccharide, meaning it is a carbohydrate molecule composed of two smaller sugar units joined together.

Monosaccharides are the simplest form of sugar, also known as 'simple sugars,' that serve as the fundamental building blocks for more complex carbohydrates like disaccharides and polysaccharides.

While both are monosaccharides with the same chemical formula ($C{6}H{12}O_{6}$), glucose has a six-membered ring structure and is the body's primary fuel, whereas fructose has a five-membered ring and is metabolized mainly in the liver.

The human body breaks down sucrose during digestion through a process called hydrolysis, which is catalyzed by the enzyme sucrase in the small intestine. This process breaks the glycosidic bond and separates the molecule into one glucose and one fructose unit.

Chemically, the sucrose molecule is identical whether it comes from fruit or sugar cane. However, in fruit, it is consumed with fiber and other nutrients, which changes how the body absorbs and processes it compared to refined table sugar.

Sucrose is a non-reducing sugar because the glycosidic bond links the reducing ends of both the glucose and fructose molecules. This linkage prevents either monosaccharide from being free to act as a reducing agent.

Yes, other common disaccharides include lactose (found in milk, made of glucose and galactose) and maltose (malt sugar, made of two glucose molecules).