Duration: 1 minutes, 12 seconds
Transcript: A common technique in genetic engineering is to insert a new gene into a loop of bacterial DNA called a plasmid. "The molecular tool used to cut DNA is a restriction enzyme such as EcoR1. The enzyme has a precise shape that allows it to run along the groove of the double helix, scanning for the base letter sequence G A A T T C EcoR1 then cuts the plasmid at this specific point... ...allowing a new piece of DNA to be inserted. When it cuts, EcoR1 leaves a sticky end, which helps the new gene to attach. The joins are then stitched together by another enzyme called DNA ligase." The genetically engineered bacteria is then grown in a culture medium. Very quickly, large numbers of the bacteria can be produced, each with a copy of the inserted gene. The bacteria duly manufacture whatever protein the gene codes for, and so the desired product is produced.