Monosaccharides and disaccharides
Monosaccharides are classed by how many carbon atoms they have.
Pentose sugars have 5 carbons and hexose sugars have 6 carbons. Both are usually ring shaped.
The carbons are numbered so that we can consistently refer to the sugar structure.
DNA strands are called 3' and 5', referring to the position of the exposed carbon in the sugar backbone.
Disaccharides are two monosaccharides joined together. All the monosaccharides listed in the table (glucose, fructose and galactose) are hexose sugars.
|Sucrose||Glucose and fructose||Fruits|
|Lactose||Glucose and galactose||Milk|
|Maltose||Two $$\alpha$$-glucoses||In germinating seeds|