Genetic Engineering

The video " Genetic Engineering" is a common technique to insert a new gene into a loop of bacterial DNA called plasmid. This is done by cutting the plasmid DNA with a restriction enzyme such as Eco RI, which allows a new piece of DNA to be inserted. The enzyme allows to run along group of a double helix, and scans for the base letters sequence GAATTC. Then the enzyme cut the plasmid at the specific point allowing a new piece of DNA to be inserted. As the plasmid is cut, Eco RI leaves a sticky-ended which helps a new gene to attach. After that the joint are stitched together by DNA ligase. In addition, the genetic engineering bacteria is growth in culture medium, so large number of bacteria can be produced very quickly. Now the genetically engineered bacteria will manufacture any protein gene coded for, so the designed product is made.
Last but not least, in our microbiology class we have learned that DNA ligase is an enzyme that seals gaps between DNA segments to form a continous DNA strand. However, DNA ligase is only one of enzymes which takes part in DNA replication, there are still more types of enzymes which we have learned in last chapter, such as DNA helicase, DNA polymerase and primase. Moreover, we will learn abour the genetic engineering in next chapter.
http://www.hhmi.org/biointeractive/media/DNAi_genetic_eng-lg.mov