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.
Cutting and Splicing DNA Molecules. If you want to insert a piece of new DNA (foreign DNA) into an existing strand you'd have to cut the existing strand, somehow position the foreign DNA, and then join the strands. This joining is called ligation and can be done with the enzyme DNA ligase. Restriction enzymes are produced by bacteria and function to protect bacteria from foreign DNA (like viruses). Restriction enzymes work by degrading foreign DNA. Restriction enzymes recognize and cut the sugar phosphate backbone of the DNA molecule at specific sites on a strand of DNA. The restriction enzyme recognition site is determined by a specific sequence of nucleotides. Thousands of restriction enzymes have been isolated, although many share the same recognition sequence.