Biotechnology Genetic Engineering

Techniques of the Past How do you get a plant or animal with certain desirable characteristics? Selective Breeding: where certain animals or plants are bred in hopes of developing certain traits in offspring Has been done by farmers for centuries May not always be successful, could take generations

Genetic Engineering Defined: changing an organism’s DNA to give the organism new traits Recombinant DNA: DNA made from two or more different organisms Produces a Genetically Modified Organism (GMO) or transgenic organism

Steps in Genetic Engineering Cutting DNA Gene of interest is cut by restriction enzymes: bacterial enzymes that recognize and bind to specific short sequences on DNA and cut the DNA between specific nucleotides http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ge/m6/s1/ http://bioweb.uwlax.edu/genweb/molecular/seq_anal/restriction_map/restriction_map.htm

DNA of a vector is also cut vector: an agent used to carry the gene of interest into another cell :could be a virus, yeast, plasmid (circular DNA from bacteria that can replicate independently of the main chromosome of a bacteria) Restriction Enzyme Animation www.Wikipedia.org

2. Making Recombinant DNA DNA from gene of interest is combined with DNA from the vector (gene splicing) Recombinant DNA is then placed in host cell http://www.odec.ca/projects/2004/lija4j1/public_html/gene.html

Many copies of the gene are made each time the host cell reproduces 3. Cloning Many copies of the gene are made each time the host cell reproduces Produces an identical copy of the gene as the cell reproduces Cell will now produce the protein coded for by the introduced gene http://en.wikibooks.org/wiki/Structural_Biochemistry/The_Stepwise_Process_of_How_DNA_is_Cloned_and_Inserted_into_the_Vector

Genetic Engineering in the Medical Field Drugs: pharmaceutical companies use bacteria to produce human proteins to help treat certain disease where the body does not produce the required proteins - ex. Insulin for diabetics, blood clotting factor for hemophiliacs Vaccines: gene for the disease’s surface protein is inserted into the DNA of a harmless virus. Immune system reacts to the surface protein without any danger of disease infecting the person. Gene Therapy: inserting healthy genes to replace faulty ones to cure a genetic disorder

Genetic Engineering In Agriculture Genetically Modified Crops: take genes from one organism and splice them into a crop, done to: - improve resistance of plant to drought, pests, herbicides (tomato) - improve nutritional value (rice) - improve yields (corn, wheat) - could be used to provide a human vaccine against certain bacteria (bananas used to vaccinate against dysentery)

Genetically Modified Animals: - use growth hormone produced by bacteria as a supplement to increase milk production growth hormone has been used to increase the size and weight of pigs and cows Transgenic animals: insert human genes into the genes of farm animals to get them to produce human proteins in their milk. Proteins are extracted from the milk and sold for pharmaceutical purposes.

Concerns Over Genetically Modified Crops Allergic reactions to gene spliced into a different food More pesticide resistant weeds if keep spraying same pesticide because it does not affect the crop Could introduced genes pass from GM crops to their wild relatives?

Cloning Taking the DNA from an adult cell, inserting it into an embryo without a nuclei, implant embryo into mother, gives birth to an organism genetically identical to original adult Difficult to do successfully because genes are not turned “on” or “off” at the right times during development (process usually takes months in sperm and years in eggs), leads to critical errors in development Very few cloned offspring survive for very long

Genetic Engineering in Forensics DNA Fingerprint: pattern of dark bands on photographic film, made when DNA is cut by restriction enzymes, stained and separated by size using gel electrophoresis Is unique for each person Can be used to establish paternity, place a person at a crime scene (DNA is taken from blood, semen, hair, bone, skin) http://geneed.nlm.nih.gov/topic_subtopic.php?tid=37&sid=38