What is stored?

Answer 1

Firstly, glycogen is a polysaccharide of glucose (made up from lots of glucose monomers), and functions as the primary short term energy storage in animal cells (mostly in liver).

When the organism needs energy, it sends a signal (hormones: adrenaline and glucagon) to the cells of the liver, so that they would start decomposing glycogen (separating it into its smaller parts - glucose). Then glucose is secreted (thrown out) into the blood, so that other cells can use it to do work.

If you need a more scientific explanation:

When a signal molecule of adrenaline or glucagon attaches to the receptor of the glycagon containing cell, the receptor activates adenylyl cyclase (transmembrane protein), which converts ATP to cAMP (cyclic adenine monophosphate). cAMP activates protein kinase A (PKA), which activates phosphorilase kinase b, which then activates glycogen phosphorilase. Only then glycogen phosphorilase catalyses the reaction of glycogen decomposure into glucose.

Answer 2

The word 'store' is a verb and a noun, and in some dictionaries, an adjective.

• The verb 'store' is to reserve or put away for future use; to stock or supply; a word for an action.
• The noun 'store' is a word for a place where merchandise is sold; a stock or supply reserved for future use; a place where things are kept for future use or sale; a word for a thing.
• The adjective 'store' is a word used to describe a noun as obtained from a commercial establishment as opposed to homemade.