Chapter 11: Gene Technology

Genetic Engineering Stanley Cohen and Herbert Boyer produced the first genetically altered organism (1973). African clawed frog DNA was isolated and inserted into the DNA of E. coli bacteria. During translation, the bacteria produced frog protein.

Genetic engineering – the process of manipulating genes for practical purposes. Recombinant DNA – DNA made from two or more different organisms.

Example: Insulin and Diabetes Prior to genetic engineering: Insulin was collected from the pancreases of slaughtered cows and pigs and then purified. After genetic engineering: The human insulin gene is incorporated into bacteria, which then create human insulin.

The Genetic Engineering Process 1. Find donor organism and identify genes 2. Re move DNA from donor and cut into fragments 3. Sort fragments by size and locate desired genes 4. Create recombinate DNA electrophoresis 5. Transfer recombinant DNA into cells 6. Grow transformed cells 7. Grow transgenic organism RecombinantDNA

Genetic Technology Basic Recombinant DNA experiment: DNA is cut Restriction enzymes recognize, bind and cut specific sequences of DNA. Cut ends are sticky.

2. Gel Electrophoresis: The cut genes placed at one end of a bed of gel An electrical field is applied to the gel. Negatively charged DNA moves toward + pole. Larger strands move slower, stay at bottom Result: Genes grouped according to size/same.

3. Create Recombinant DNA DNA ligase attaches the “sticky ends” of DNA to another DNA molecule called Plasmid.

b. Vector carries plasmid into host cell

c. The gene of interest is copied as the host cell reproduces.

DNA Probes: Probes are radioactive or fluorescent labeled RNA or single stranded DNA pieces that are complementary to the gene of interest. Used to look for a specific DNA sequence. If the gene of interest is present, the probe will bind to it and mark it.

DNA Fingerprints: Using an assortment of probes a DNA Fingerprint can be created. Uses: Comparison of samples (crime scenes) Determining relatedness (paternity)

Polymerase Chain Reaction: PCR makes many copies of selected segments of DNA. Important anytime that only a small amount of DNA is available Diagnosing genetic disorders Solving crimes Studying archeological evidence

Incan Mummy from the Andes - Frozen for 500 years

Polymerase Chain Reaction: Step 1: DNA sample is heated, strands separate. Step 2: Sample is cooled and primers (short pieces of artificial DNA) are added that bind to DNA in places where copying can begin. Step 3: DNA polymerase and free nucleotides are added. DNA is copied.

Genetic Engineering in Medicine Genetically engineered proteins that treat illnesses: Anticoagulants – dissolve blood clots Factor VIII – promotes blood clotting in hemophiliacs Growth factors – Burns and ulcers Human growth hormone – growth defects Interferon – Viral infections and cancer

Genetically engineered vaccines: Insert genes that encode a pathogen’s surface proteins into the DNA of harmless bacteria. Build immunity without risk of causing disease.

Gene therapy to treat or cure genetic disorders and diseases: Gene therapy involves putting a healthy copy of a gene into cells of a person whose copy of the gene is defective. Could be useful to treat cancer, cystic fibrosis, hemophilia, etc. Obstacle – how to get the genes safely into the right cells and activated.

Human Genome Project: Sequenced the entire human genome and mapped all gene locations in 2003. Many gene functions are still unknown.

Genetic Engineering in Agriculture Genetic engineering is used to alter crop plants: Drought tolerance Control over fruit ripening Improved nutritional value Weed-killer resistance Insect resistance

75-80% of all processed foods contain GM products At least 50 of the most common food crops are GM (potatoes, corn, soybeans, sugar beets) Long term effects have not been evaluated GM food labels are not required in the U.S.

Genetic engineering is used to alter livestock: It is common for farmers to add rBGH (growth hormone) to the diet of cows to increase milk or meat production. Unclear what long term effects this could have on human health.

Livestock can be altered to have greater nutritional value or less impact on the environment.

Genetic engineering is using animals to make products: Genes are added to farm animals to produce proteins from other organisms. These proteins are collected from the animal’s milk and sold for pharmaceutical or commercial purposes. These animals are transgenic because they have foreign DNA incorporated into their cells.

Cloning: In 1997, Ian Wilmut became the first person to successfully clone specialized cells from an adult mammal (sheep). Since then, cows, mice, coyotes, dogs, wolves, monkeys and several other animals have also been cloned.