Some important concepts are:
- So many OH groups make carbohydrates polar. The small molecules such as glucose are highly water soluble and insoluble in most organic solvents.
Bigger molecules such as starch can wet well with water but are too big to dissolve. Some carbohydrate polymers such as dextran do dissolve fairly well.
- Sugars are good foods but not as energy-rich as fats that are less oxidized.
- Intermediates in the metabolism of sugars are building blocks for other biochemicals.
- Bioenergy comes from stepwise release as molecules transverse a pathway. The alternative would be one step rapid oxidation such as burning, and that is not compatible with living systems (no steam boiler in your stomach).
- Sugars exhibit much sterioisomerism, but most of the possibilities do not occur in nature or are quite rare.