Biological Molecules
Testing
Reducing Sugar Test
Carbohydrates
Monosaccharide
A monosaccharide is the smallest repeating unit of a carbohydrate molecule. The most common example is glucose.
Glucose
Glucose is an aldehyde with the formula C6H12O6. It plays a major role in providing energy for an organism in the form of respiration. Glucose:
- can be linear or cyclic but is mostly found in cyclic form
- has 2 isomers in cyclic form named alpha and beta
- is a monomer that can join together to form polysaccharides such as:
- starch
- cellulose
- glycogen
The carbons in glucose are numbered from the functional group (aldehyde).
- Carbon 1 and 4 form glycosidic bonds when 2 glucose molecules join together
- A water molecule is produced during glycosidic bonding making it a condensation reaction
Polysaccharide
A polysaccharide is a repeating chain of monosaccharides. Their size is much greater making them hard to transport through diffusion. Polysaccharides can be:
- branched or unbranced
- made up of either alpha or beta glucose
- broken down through a hydrolysis reaction
- used as compact storage molecules
| Polysaccharide | Glucose | Branched |
|---|---|---|
| Amylose | Alpha | close |
| Amylopectin | Alpha | check |
| Cellulose | Beta | close |
| Glycogen | Alpha | check |
A hydrolysis reaction is the opposite of a condensation reaction. Water is required to breaak glycosidic bonds.
Lipids
Phospholipid
A phospholipid has 1 hydrophilic phosphate head and 2 hydrophobic fatty acid tails. The phosphate group and the fatty acids are attached to a glycerol molecule.
A fatty acid tail can be saturated or unsaturated. An unsaturated fatty acid will have double bonds between carbon atoms which increase the fluidity of membranes.
Proteins
A protein is made up of many amino acids.