Starch is a storage carbohydrate used by plants.
When plants photosynthesize the use the energy from sunlight to convert carbon dioxide and water into sugars and oxygen.
Glycogen is a storage carbohydrate used by animals.
Cellulose is a polysaccharide that is used in plant cell walls to maintain their structure.
Starch and cellulose are both polymers of glucose, but humans cannot digest cellulose. The difference in the bonding arrangement might seem minor, but enzymes must fit a molecule very precisely. Thus, enzymes that break down starch do nothing to cellulose.
Humans take in amino acids and utilize them to synthesize the polymers that are called proteins.
There are 10 amino acids which humans cannot synthesize themselves and must be in the diet, these are called essential amino acids.
Humans also take in carbohydrates and use the break down of the carbohydrate as an energy source.
When either of these is taken in in quantities above that that is necessary for the body, they are converted into fats in animals and oils in plants.
Fats and oils are a long term storage for energy sources.
Animal fats are wither saturated or unsaturated, but most are saturated.
Unsaturated fats are believed to lower cholesterol levels in humans.
Saturated fats and cholesterol are thought to contribute to hardening of the arteries.
Fats are stored in adipose tissue which has an insulating function, a padding (protective) function, as well as a storage function.
The triglyceride structure of fats and oils. Note the glycerol structure on the left and the ester structure on the right. Also notice that R1, R2, and R3 are long-chained molecules of 12, 14, 16, 18, 20, 22, or 24 carbons that might be saturated or unsaturated.
Polymers are long molecules with repeating structures of simpler molecules.
Synthetic polymers, the polymer unit, and some uses of each polymer.
Petroleum and coal as sources of raw materials for manufacturing synthetic polymers.