BRAINCAKEMonosaccharides
Monosaccharides are the simplest carbohydrates: single sugar units that cannot be hydrolysed into smaller sugars. Their general formula is (CH2O)n, and they are named by the number of carbon atoms:
• trioses (3C), such as glyceraldehyde, made in photosynthesis and respiration
• pentoses (5C), such as ribose (in RNA and ATP) and deoxyribose (in DNA)
• hexoses (6C), such as glucose, fructose and galactose
In solution, pentoses and hexoses mostly form rings. Glucose, C6H12O6, forms a six-membered ring of five carbons and one oxygen. The carbons are numbered 1 to 6, starting next to the ring oxygen.
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Key terms in this lesson
- isomer
- One of two or more molecules with the same molecular formula but a different arrangement of atoms.
- reducing sugar
- A sugar that can donate electrons to, and so reduce, another chemical, such as the Cu2+ ions in Benedict's reagent.
More in Biological Molecules
- Organic Compounds
- Carbohydrates
- Disaccharides
- Test for Sugars
- Polysaccharides
- Starch
- Test for Starch
- Glycogen
All 25 lessons in Biological Molecules · All Edexcel AS-level Biology topics