Sugars: Monosaccharides, Glycosidic Bonds & Polysaccharides
Katja Kobow · 9 concepts · 10 questions
Concept 1 / 9
What Are Sugars? Mono-, Di- and Polysaccharides
Sugars (carbohydrates) are organic molecules that serve as both building blocks and an energy source in cells. They are organized by size:
| Class | Definition | Examples |
|---|---|---|
| Monosaccharide | Single sugar unit (the basic unit) | Glucose, fructose, galactose, ribose |
| Disaccharide | Two monosaccharides linked | Maltose, sucrose, lactose |
| Polysaccharide | Many units linked into chains | Glycogen, starch, cellulose |
Monosaccharides are the basic units. They follow the general formula (CH₂O)ₙ, where n can be 3, 5, 6, 7 or 8. Each unit has several hydroxyl (–OH) groups.
Key size names from the slides:
- Hexose = 6 carbons (e.g. glucose, fructose, galactose)
- Pentose = 5 carbons (e.g. ribose, deoxyribose)
Distribution-of-molecules slide: in a cell, sugar is the subunit whose macromolecule is the polysaccharide — just as amino acids build proteins and nucleotides build nucleic acids. Polysaccharide makes up ~2% of a bacterial cell's dry chemicals.