2.5 carbohydrates: monosaccharides & disaccharides

What are monosaccharides

The simplest form of carbohydrates, also known as 'simple sugars'.

What is the general formula for monosaccharides?

Monosaccharides have the formula (CH₂O)_n where n can be any number from 3 to 7.

What is the difference between pentose and hexose sugars?

Pentose sugars have 5 carbon atoms whereas hexose sugars have 6 carbon atoms. 

What is the formula for glucose? 

Glucose has the formula C₆H₁₂O₆. 

What are the names of the two glucose isomers? 

1. Alpha-glucose

2. Beta-glucose

What is the difference between alpha-glucose and beta-glucose?

The orientation of the hydroxyl group on carbon 1.

What is the primary energy source in animals and plants?

The primary energy source is glucose.

Why is glucose a good energy source?

Glucose is soluble and its bonds store lots of energy.

What are disaccharides?

Carbohydrates formed when two monosaccharides join together

Name three examples of disaccharides.

1. Maltose

2. Sucrose

3. Lactose

Name the monosaccharides found in maltose, sucrose, and lactose. 

How are disaccharides formed?

Disaccharides are formed via condensation reactions.

The hydroxyl group (OH) of one monosaccharide reacts with the hydroxyl group (OH) of another monosaccharide.

This forms a glycosidic bond and releases a water molecule. 

How are disaccharides broken down?

Disaccharides are broken down via hydrolysis reactions.

A water molecule is added to a disaccharide and the glycosidic bond is broken to release the 2 monosaccharides.