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Some basic tools • Restriction enzymes molecular scissors) make precise, reproducible cuts in DNA. • Electrophoresis gels that separate protein or DNA fragments according to size, allowing isolation and characterization. • DNA sequencing techniques, allow the exact sequence determination of sequence (ATCGs) of pieces of DNA • Vectors, e.g. plasmids, move DNA into convenient host organisms (e.g. bacterial cells) • Cloning: the production of multiple genetically identical pieces of DNA or organisms • Polymerase Chain Reaction (PCR): a technique for repetitively replicating sections of very small amounts of DNA until any desired amount is produce. – Xeroxing DNA • Bioinformatics: the interface of computers and biological data. There is already a vast amount of data available, far more than can be comprehended by the human mind. New computer algorithms (procedures for data analysis) are being developed, and people specialize in the area of computer manipulation and analysis of biological data are in demand
Biotechnology, using biological systems, has several distinct advantages over non-biological systems. • Required Biological processes can be caused to occur under ambient temperatures and pressure, and neutral pH. • Most of the biological processes do not require potentially polluting heavy metal catalysts. Note that biological reactions also yield byproducts, but most of these are biodegradable and do not become a main source of pollution. • Depending on the organisms chosen, biological processes can use a variety of substrates ranging from simple inorganic compounds, such as carbon dioxide, nitrogen oxides and hydrogen to complex carbohydrates, hydrocarbons and phenolic compounds such as lignin. Many of these compounds can not serve as substrates for chemical synthesis. • A variety of simple to complex products can be made by biological processes, ranging from alcohol, organic acids, to peptides, complex proteins, etc. Some of these compounds can not be made easily by chemical synthesis, for example, monoclonal antibodies • Multi-step reactions are possible and are more easily done using organisms than by doing chemical reactions. One microbe can do 20 steps at once. • Biological systems can (potentially) carry out unique & stereospecific reactions, some of which are not possible using chemical systems. Biosynthesis of drugs can result in optically pure products which can have fewer side effects • Exactly the identical required product can be produced e.g. human therapeutic proteins
Some Applications of Biotechnology Biotechnology is still in its infancy, but is having profound implications for our society and our future. • DNA fingerprinting: Tiny amounts of DNA from a crime scene, a blood sample, a semen stain, etc., can be amplified by PCR, cut by restriction enzymes, and compared after electrophoresis. These techniques make it possible to identify rapists, fathers in disputed paternity suits, elephant tusks from protected herds, and many more forensic applications.
Bioengineered products for medicinal use. Such products are currently available for sale, including products to treat heart attack, stroke, breast cancer, multiple sclerosis, and many more. E.g. • producing human insulin for diabetics in bacterial or yeast cells • producing tissue plasminogen activator for heart attack victims in bacterial or yeast cells • producing human growth hormone for people with pituitary dwarfism in bacterial or yeast cells • the introduction of essential vaccines into bananas to be eaten by children. • Biotechnology has been used to create many improved vaccines e.g. for the rinderpest virus in cattle Gene therapy: correct enzyme deficiencies due to faulty genes by introducing "healthy" genes. E.g. SCID, bubble children
Biopharming. It’s the process of using genetically altered or transgenic livestock to produce pharmaceuticals and other medically important products. • Transgenic animals with human-benefiting proteins in their milk current advancements in cloning make pharming feasible on an industrial scale. E.g. spider silk protein AT ryn, an american company Has just been given the go ahead to produce human anti thrombin in goats in Europe. This is used as an anticoagulant to treat a rarecongenital disease Advantages offered • Decreased cost • Ease of production • Lower cost to environment (debatable) • no danger from using mammalian cells and tissue culture medium that might be contaminated with infectious agents
Transgenic plants: the major challenge of the 21st century will be feeding the growing human race by increasing food production, especially with food crops. Genes can be introduced into crop plants to improve growth in many ways, including: • 1. better insect resistance. • Example: "Bt" corn. The bacterium Bacillus thuringiensis (Bt) kills many insects that cause plant diseases because it produces a protein crystal that damages insect GI tracts. The gene for this protein has been moved from bacteria into corn, making insect-resistant corn. • 2. better disease resistance: A genetically engineered sweet potato is now available in Nairobi. Engineered to resist disease, it is expected to increase yields by up to 60 per cent. No pesticide is required. Unfortunately, more than half of the conventional sweet potato crop is destroyed by a virus which causes black marks on the tubers. • 3. higher tolerance to herbicides. • Example: RoundupTM -tolerant corn, soybeans, and sugar beets, have been created by moving gene for herbicide resistance from a different plant. RoundupTM, a powerful herbicide, can then be used to kill all weeds, without affecting the crop.
Advantages • Glycoproteins can be made (bacteria like E. coli cannot do this). • Virtually unlimited amounts can be grown in the field rather than in expensive fermentation tanks. • There is no danger from using mammalian cells and tissue culture medium that might be contaminated with infectious agents. • Purification is often easier Some of the proteins that are being produced by transgenic crop plants: • human growth hormone with the gene inserted into the chloroplast DNA of tobacco plants. • humanized antibodies against such infectious agents as • HIV • respiratory syncytial virus (RSV) • sperm (a possible contraceptive) • herpes simplex virus, HSV, the cause of "cold sores" • protein antigens to be used in vaccines • other useful proteins like lysozyme and trypsin • greater ability to resist salt. Would allow crop plants to be grown in many areas not currently suitable for cultivation because of salt. • Better storage and taste. Example: the Flavr SavrTM tomato has been genetically modified so tomatoes can stay on the vine longer, ripen to better flavor.
Basic research. Much biological research carried out today is based in the tools of DNA technology, including: • sequencing the entire genomes of living organisms (the human genome was recently completed) • using DNA probes to detect the full range of living organisms. Using these techniques has revealed that only about 10% of microbes have actually been grown in laboratories, 90% of life's diversity remains uncultured by us • Understanding development and cancer • Understanding disease • Investigating proteomics • Diagnosing disease
Some Public Concerns about DNA TechnologyPublic concerns focus on issues of human health and environmental safety. Examples: • nutritional impact of modifying food • potential toxicity of inserted genes or their products • allergen-inducing potential of the products of inserted genes • transfer of genes encoding antibiotic resistance • impact on biodiversity of planting huge quantities of engineered crops that encourage massive use of herbicides • potential escalation of problems as insects and weeds develop resistance to engineered gene products