The MacBook Pro follows, with its prices going from $2,199 down to $1,999 for the 15-inch version (and from $1,499 for the 13-inch version down to $1,299). That's a break from traditional Apple pricing, where prices would remain the same generation over generation, with updated components adding value.
Restriction enzymes can also be used to generate compatible ends on PCR products. In all cases, one or more restriction enzymes are used to digest the DNA resulting in either non-directional or directional insertion into the compatible plasmid.
You can think of restriction enzymes as little molecular scissors that slide along the DNA and cut the sugar-phosphate backbone wherever they find their restriction site. The figure shows how a restriction enzyme can make a cut in a circular piece of DNA and turn it into a linear piece.