The ability of carbon to form long chains is called Catenation.  
 
        
                    
             
        
        
        
There ar 5 in nitrogen, 20 in hydrogen, and 5 in chlorine. In all that’s 30 compounds.
        
             
        
        
        
restricted endonucleases are used to cut DNA into smaller fragments
 
        
             
        
        
        
Something with higher electric potential than the ground or a defined null or neutral point. Electrons flow from the positive point in a circuit. See also negative, null, and potential.