Disaccharides are formed by the condensation of two monosaccharides: maltose (glucose + glucose), sucrose (glucose + fructose), lactose (glucose + galactose)
Two simple sugars (monosaccharides) can join together to form a double sugar called a disaccharide. Maltose, sucrose, and lactose are the three disaccharides you need to know.
Formula
2 monosaccharides → disaccharide + H₂O
Real World
Sucrose is the white table sugar in Tate & Lyle's products — a disaccharide of glucose and fructose joined by a glycosidic bond; it cannot be absorbed directly and must first be hydrolysed by sucrase in the gut wall.
Exam Focus
Memorise all three disaccharide compositions exactly — exam questions frequently ask you to state which monomers form a named disaccharide.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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