Practice question

Restriction enzymes are classified by cleavage pattern into blunt and cohesive end generators depending on whether they cut opposite strands at same position or offset. SmaI recognizes the palindromic hexanucleotide CCCGGG and incises between central C and G on both strands, CCC/GGG, producing blunt termini with no overhang. This central cut yields DNA fragments with fully base-paired ends requiring higher ligase concentration for joining. SmaI activity is useful for blunt-end cloning, deletion mapping and generating non-directional inserts where cohesive overlap is undesirable for subsequent manipulations.