Forming the Glycosidic Bond
- To make monosaccharides more suitable for transport, storage and to have less influence on a cell’s osmolarity, they are bonded together to form disaccharides and polysaccharides
- Disaccharides and polysaccharides are formed when two hydroxyl (-OH) groups (on different saccharides) interact to form a strong covalent bond called the glycosidic bond (the oxygen link that holds the two molecules together)
- Every glycosidic bond results in one water molecule being removed, thus glycosidic bonds are formed by condensation
Glycosidic Bond Formation Diagram
The formation of a glycosidic bond by condensation between two monosaccharides (glucose) to form a disaccharide (maltose)
- Each glycosidic bond is catalysed by enzymes specific to which OH groups are interacting
- As there are many different monosaccharides this results in different types of glycosidic bonds forming (e.g maltose has a α-1,4 glycosidic bond and sucrose has a α-1,2 glycosidic bond)
Glycosidic Bond Formation Diagram
The formation of a glycosidic bond by condensation between α-glucose and β-fructose to form a disaccharide (sucrose)
Glycosidic Bond Formation Diagram
The formation of glycosidic bonds to create a polysaccharide (amylopectin)
Types of Glycosidic Bonds Table
Sugar | Type of Glycosidic bond | Type of Molecule |
Maltose | α 1,4 | Disaccharide |
Sucrose | α 1,2 | Disaccharide |
Cellulose | β 1,4 | Polysaccharide |
Amylose | α 1,4 | Polysaccharide |
Amylopectin | α 1,4 and α 1,6 | Polysaccharide |
Examiner Tip
Make sure you can identify where the glycosidic bond is in a carbohydrate.