Answer:
An old penny rusting
Explanation:
A penny forming rust is the penny being chemically altered and changing form as opposed to dissolving sugar in water, which is still sugar, just mixed with water. It doesn't change the chemical makeup of the water or sugar.
 
        
             
        
        
        
It is important to understand because it's the way all cells reproduce (except sperm and egg cells, they do meiosis), and our cells are the essential parts of our whole being.
        
             
        
        
        
Peptide bonds link amino acids together to form polypeptide chains