Overview
This lecture covers the basic structure, properties, and types of carbohydrates, focusing on simple sugars, their solubility, and how they combine to form larger molecules.
Monosaccharides and Structure
- Carbohydrates are made of simple sugars called monosaccharides.
- Monosaccharides typically contain 5 or 6 carbon atoms.
- Glucose is a common monosaccharide, with the formula C₆H₁₂O₆ and a 1:2:1 ratio of carbon:hydrogen:oxygen.
- Glucose contains many oxygen atoms, making it a polar molecule.
Polarity and Solubility
- The polar covalent bonds in glucose allow it to dissolve easily in water.
- Water molecules form hydration spheres around individual sugar molecules, enabling them to remain in solution.
- The positive end of water is attracted to negative ends (like oxygen in glucose), facilitating dissolving.
Solutions and Components
- A solution is a uniform mixture of two or more substances.
- The solvent is the substance doing the dissolving (usually water in biology).
- The solute is the substance being dissolved (e.g., sugar in water).
- Sugar’s polarity allows it to be an effective solute in aqueous solutions.
Disaccharides, Polysaccharides, and Polymers
- Two monosaccharides can join to form a disaccharide (e.g., glucose + fructose forms sucrose).
- Multiple monosaccharides linked together form polysaccharides, a type of polymer.
- Starches and glycogen are polysaccharides; glycogen, stored in muscle and liver, is used for energy storage.
Key Terms & Definitions
- Monosaccharide — a simple sugar molecule, basic unit of carbohydrates.
- Disaccharide — two monosaccharides linked together.
- Polysaccharide — a long chain of monosaccharides; a complex carbohydrate.
- Polymer — a large molecule made from repeating units (monomers).
- Solvent — the substance that dissolves another (usually water).
- Solute — the substance being dissolved.
- Solution — a uniform mixture of solvent and solute.
- Hydration sphere — water molecules surrounding a solute when dissolved.
Action Items / Next Steps
- Review the structure and formula of glucose.
- Practice identifying and drawing monosaccharides, disaccharides, and polysaccharides.
- Read textbook section on carbohydrates and polymers.