The Two Forms of Glucose
- The most well-known carbohydrate monomer is glucose
- Glucose has the molecular formula C6H12O6
- Glucose is the most common monosaccharide and is of central importance to most forms of life
- There are different types of monosaccharide formed from molecules with varying numbers of carbon atom, for example:
- Trioses (3C) e.g. glyceraldehyde
- Pentoses (5C) e.g. ribose
- Hexoses (6C) e.g. glucose
- Glucose exists in two structurally different forms – alpha (α) glucose and beta (β) glucose and is therefore known as an isomer
- This structural variety results in different functions between carbohydrates
Alpha and Beta Glucose Diagram
Straight chain and ring structural formula of alpha & beta glucose
- Different polysaccharides are formed from the two isomers of glucose
Structure of polysaccharides table
Polysaccharide | Alpha Glucose | Beta Glucose |
Starch | ✓ | X |
Glycogen | ✓ | X |
Cellulose | X | ✓ |
Examiner Tip
You must be able to recognise and draw the isomer rings of α and β glucose.