2.1.2 Carbohydrates

Carbohydrates

Compounds containing carbon, hydrogen, and oxygen.

Monosaccharide

Single sugar unit.

Disaccharide

Sugar composed of two monosaccharides.

Polysaccharide

Molecule made of many monosaccharides.

Pentose sugar

Monosaccharide with 5 carbons.

Hexose sugar

Monosaccharide with 6 carbons.

Triose sugar

Monosaccharide with 3 carbons.

Furanose ring

5-atom ring in a monosaccharide.

Pyranose ring

6-atom ring in a monosaccharide.

Isomer

Molecule with the same formula but different structure.

Alpha-glucose

Glucose with the hydroxyl group below the ring.

Beta-glucose

Glucose with the hydroxyl group above the ring.

Reducing sugars

Sugars that reduce Cu2+ ions.

Non-reducing sugar

Sugar that doesn't reduce Cu2+ ions.

Qualitative test

Determines presence or absence of a chemical.

Semi-quantitative test

Estimates concentration range.

Quantitative test

Measures exact concentration.

Glycosidic bonds

Bonds between monosaccharides in polysaccharides.

Iodine Test

Adding iodine solution to a sample to detect the presence of starch.

Starch

A polysaccharide that, when present, turns the iodine solution blue-black.

Starch Helix

Part of a starch molecule coiled due to weak hydrogen bonds.

Iodide Ions

Present in iodine solution, they form a complex with starch in the helix.

Cellulose

A structural polysaccharide found in plant cell walls, made of beta-glucose with β(1-4) glycosidic bonds.

β(1-4) Glycosidic Bonds

Bonds between beta-glucose molecules in cellulose, forming straight chains.

Hydrogen Bonds

Many form between cellulose molecules, giving cellulose fibers high tensile strength.

Microfibril

Cellulose molecules combine to form these structures.

Macrofibril

Combination of microfibrils, forming larger structures in cellulose fibers.

Permeable

Term applicable to cellulose cell walls due to gaps between fibers, not to cellulose itself.