Metabolism has two parts: Catabolism breaks down complex molecules into smaller building block molecules - think proteins -> amino acids. Then anabolism uses those building blocks to build up larger molecules for growth and maintenance. Crystals don't do the catabolism part.
Looks like cell's phospholipid bilayer is anabolized just like an "endothermic" crystal : no need to cross a potential barrier (and releases energy instead of consuming it)?
On the other hand, other forms of anabolism require crossing an energy barrier (and consumes energy) ?
While catabolysm is the inverse operation : crosses a barrier, but releases energy?
The formation/destruction of "exothermic" crystals like dissolution of Sodium Hydroxide if put in contact with water is I guess similar to above two reactions ? (Or better example: explosives)
