Ch. 11 NotesGene Technology By: Brianna Shields January 3, 2006
DO NOW Anti-Sense DNA Strand: ATTAGCATTGCC • Transcribe this sequence into a strand of mRNA • Translate this sequence into the resulting protein • If a tRNA attaches to the second codon of the mRNA, what would the tRNA’s anticodon be?
GOALS • Describe four basic steps commonly used in genetic engineering experiments • Evaluate how restriction enzymes and the antibiotic tetracycline are used in genetic engineering • Relate the role of electrophoresis and probes in identifying a specific gene • Summarize the two major goals of the human genome project • Describe how drugs produced by genetic engineering are being used • Summarize the steps involved in making a genetically engineered vaccine • Describe how gene therapy is being used to try to cure genetic disorders • Identify two different used for DNA fingerprints • Describe three ways in which genetic engineering has been used to improve plants • Summarize two ways in which genetic engineering techniques have been used to modify farm animals • Summarize the cloning of sheep through the use of differentiated cells
Genetic Engineering Manipulation of genes for practical purposes Involves building recombinant DNA Made from 2 or more different organisms Steps of Genetic Engineering
First genetically altered organism was created when the gene coding for rRNA in african clawed frog was inserted into e. coli. The Bacteria then produced the frog rRNA during transcription.
Genetic Engineering Insulin for diabetics used to be extracted from cow or pig pancreas Now, human insulin gene transferred to bacteria Steps of Genetic Engineering
Genetic Engineering Steps 1. Bacterial restriction enzymes cut Insulin gene out of human DNA A space into vector DNA (virus, yeast or plasmid that will carry insulin gene) Plasmid- circular DNA that can replicate on its own Steps of Genetic Engineering
Genetic Engineering Steps 2. DNA ligase helps insulin gene insert into vector DNA Vector taken up by host cell Sticky ends (complementary base pairs) of insulin gene and plasmid allow DNA’s to bond Steps of Genetic Engineering
Genetic Engineering Steps 3. Gene Cloning- many insulin gene copies made as host bacteria reproduces Steps of Genetic Engineering
Genetic Engineering Steps 4. Screening- Cells with vector are detected By growth on tetracycline antibiotic plate (only cells with vector will grow- they are resistant) Cells allowed to transcribe and translate protein from insulin gene Steps of Genetic Engineering
Confirmation of a cloned gene (southern blot) 1. DNA from bacterial clones removed and cut by restriction enzymes Steps of Genetic Engineering
Confirmation of a cloned gene (southern blot) 2. Gel electrophoresis- electric field separates DNA fragments by size Negative DNA attracted through a gel to a positive pole Smallest DNA is fastest Band patterns form Gel soaked in chemical to cause double stranded DNA to become single stranded Steps of Genetic Engineering
Confirmation of a cloned gene (southern blot) 3. DNA bands transferred onto filter paper Paper moistened with probe solution Probe- radioactive or fluorescent DNA that will base pair with gene of interest) Steps of Genetic Engineering
Confirmation of a cloned gene (southern blot) 4. Complementary DNA will bind to probe to form visible bands Steps of Genetic Engineering
WEBSITES • Gel Electrophoresis Lab • More on Gel Electrophoresis • Gel Electrophoresis Animation • Gel Electrophoresis • Southern Blot
Assessment One • Apply the four steps commonly used in genetic engineering experiments to describe the cloning of a human gene • Relate the role of DNA “sticky ends” in the making of recombinant DNA • Summarize how cells are screened in genetic engineering experiments • Evaluate the role of probes in identifying a specific gene • A student performing electrophoresis on a DNA sample believes that her smallest DNA fragment is the band nearest the negative pole of the gel. Do you agree with her conclusion? Explain • Many genetic engineering experiments are performed in bacteria using circular DNA molecules called?
Human Genome Project 3.2 billion DNA base pairs in human genome DNA in human cell is 6 ft in length Only 1-2% of DNA codes for proteins (exons- about 1 inch) 98-99% of DNA is nonsense introns 30,000-40,000 genes Human Genome Project
Genetically engineered drugs Many illnesses result due to lack of a proteins Ex: Juvenile diabetes lacks insulin Companies now use bacteria to produce the protein Ex: Hemopheliacs can avoid bad blood transfusions by getting the VII protein factor they’re missing from GE Genetically Engineered Drugs and Vaccines
Vaccines Weakened or dead pathogen injected into body Immune system recognizes pathogen’s surface proteins Antibodies made to combat future infection by virulent pathogen Genetically Engineered Drugs and Vaccines
Vaccines In past, vaccines had potential to infect Now, gene for virus’s surface proteins can be inserted into harmless virus Immune system recognizes surface protein as harmful and creates antibodies Ex: Herpes and Hepatitis B now genetically engineered Working on Malaria Genetically Engineered Drugs and Vaccines
DO NOW • 1. What do you call the step in genetic engineering where cloned cells are allowed to reproduce on agar containing antibiotics to separate out the cells with the gene of interest? • 2. During which process is an electrical field used to separate DNA fragments of varying sizes? • 3. Which type of DNA fragments travel the farthest in the above mentioned process?
DNA Fingerprinting DNA sequencing technology used to determine a DNA fragment’s sequence Two individual’s DNA restriction fragment lengths (RFLP’s) will differ RFLP’s used to identify people and determine paternity DNA Fingerprinting
DNA Fingerprinting Viewed as a pattern of dark bands on film DNA restriction fragments are separated on a gel, probed and exposed to X ray film Each individual shows unique banding pattern Can compare patterns to determine identity or relatedness DNA Fingerprinting
DNA Fingerprinting Can be accomplished with just blood, semen, bone or hair Helps in forensic investigation and identification of genetic disorders DNA Fingerprinting
WEBSITES • Human Genome Project • Recombinant DNA Technology Video • Gene Sequencing Interactive • Exploring a Stretch of DNA • BioInteractives • Crack the Code Game • Steps in Cloning a Gene Video Clip
Assessment Two • Relate the use of genetic engineering to the treatment of human illnesses such as hemophilia • Relate genetic engineering techniques to the making of vaccines • Name the process in which a healthy copy of a gene is inserted in the cells of a person with a defective version of the gene. • List the two ways in which DNA fingerprinting has been useful to society.
Agriculture Farmers used to select seeds from the best plants to replant to improve successive generations Favorable characteristics now added to plants by manipulating their genes Genetic Engineering in Agriculture
Plants can be genetically engineered to: 1. Tolerate drought conditions 2. Adapt to different soils, climates and environmental conditions 3. Become resistant to herbicides- weed killer like glyphosate Genetic Engineering in Agriculture
Plants can be genetically engineered to: 4. Become resistant to insects Gene added to plant to injure gut of chewing insects 5. Add nutritional value to food Genes added to rice to add iron and beta carotene Combats iron deficiency and poor vision in Asia Genetic Engineering in Agriculture
Risks of GM 1. Increased use of a weed killer (harmless to humans and crops) may lead to toxin resistant weeds Genetic Engineering in Agriculture
Risks of GM 2. New genes added to crops can cause allergy problems for consumers Genetic Engineering in Agriculture
Risks of GM 3. Genes can flow naturally between closely related species 4. Pests can eventually become resistant to GM toxins Genetic Engineering in Agriculture
Gene Technology in Animal Farming A. Instead of mating cows with favorable traits, farmers add growth hormone to their diet to increase milk production Used to get hormone from brains of dead cows, now bacteria used to produce it Genetic Engineering in Agriculture
Gene Technology in Animal Farming B. Human genes added to animal genes to get them to produce human proteins in their milk Companies then extract and sell the proteins Creates “Transgenic Animals”- have foreign DNA in their cells Genetic Engineering in Agriculture
Gene Technology in Animal Farming C. Cloning of animals can take place from differentiated (specialized) cells- not just from embryonic cells Found by Wilmut Sheep Dolly (1996)- mammary cells and egg cells of different sheep fused by electric shock Embryo implanted into surrogate mother Genetic Engineering in Agriculture
Cloning Problems 1. Animals can be fatally large 2. Developmental problems 3. Genes can be turned on too early in development Genomic Imprinting can temporarily turn genes off by adding a methyl group, preventing transcription Genes can later be turned back on, when time is right Genetic Engineering in Agriculture
WEBSITES • Engineer a Crop • Guess What’s Coming to Dinner • Genetically Modified Organisms