Cukry jako cząsteczki magazynujące energię

Simple sugars, such as glucose, are a primary source of energy in most living organisms. When food is abundant, organisms convert these simple sugars into specialized energy storage molecules, such as starch and glycogen.

When the food supply gets limited, the energy stored in the covalent bonds of these complex storage molecules can be utilized by breaking them back down into simpler forms.

Starch is a long polymer of glucose that serves as an energy reserve in plants. When plants are unable to photosynthesize, starch is broken down into easily usable glucose units.

Tubers such as potatoes and grains such as rice, wheat, and corn are particularly rich in starch.

Humans and all other animals store excess glucose in the form of glycogen — a large, branched polymer of glucose residues, in the liver and muscle cells.

During fasting, glycogen is broken down into glucose 1-phosphate, which can directly enter glycolysis to produce energy.