Practice question

Restriction enzymes recognize specific palindromic sequences of four to eight nucleotides with high precision. A single nucleotide polymorphism altering even one base within this motif abolishes hydrogen bonding complementarity needed for enzyme binding and catalysis, preventing phosphodiester hydrolysis. The enzyme no longer recognizes mutant site, so digestion pattern changes, forming basis for restriction fragment length polymorphism analysis. The site does not become shorter or more cleavable, nor does polymorphism inherently add labels. Loss of cleavage explains RFLP markers linked to disease mutations.