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Transcript
Biotechnology Genetic engineering • Involves manipulating the DNA of one organism in order to insert the DNA of another organism • Examples • Inserting a gene for bioluminescence into various organisms, which can be used to study gene expression, cellular processes, disease development, and selecting traits which may be beneficial to humans • Uses: • To increase or decrease the expression of specific genes in selected organisms • Applications in human health (disease prevention, preventing spread of infectious diseases) and agriculture • Genes can be manipulated to show desirable traits • Genome – all of the DNA in an organism • Can contain millions and millions or nucleotides • In order to study a specific gene, DNA tools can be used to manipulate DNA and to isolate genes from the rest of the genome • Examples – restriction enzymes, gel electrophoresis • Recombinant DNA technology – A new DNA molecule created by combining DNA from two different sources • Used to create recombinant DNA to study individual genes and genetically engineered organisms and in the treatment of certain diseases • Requires large quantities (how done – see next slide) • How large quantities of recombinant DNA is made: • Requires a carrier, or vector, such as viruses and plasmids (small, circular, double-stranded DNA molecules that occur naturally in bacteria and yeast cells) • Plasmid and DNA fragment can be joined to make recombinant DNA • Vector transfers the recombinant DNA into a bacterial cell called a host cell • Host cell then makes large quantities of the recombinant DNA to be made • Transgenic organisms – organisms that are genetically engineered by inserting a gene from another organism. • Animals, plants and bacteria used for research, medical, and agricultural purposes • Ex. of transgenic animals: • Mice, fruit flies, and worms used to study diseases and develop treatments • Livestock produced to improve food supply and human health • Goats engineered to secrete a protein used to prevent human blood from forming clots during surgery • Fish that grow faster • Working to produce chickens & turkeys that are resistant to disease; transgenic organisms may someday be a source of organs for transplants • Ex. of trangenic plants: • Plants have been engineered to be resistant to insect or viral pests, such as soybeans, corn, cotton, and canola • Developing peanuts and soybeans that do not cause allergic reactions, rice plants with increased iron and vitamins that could decrease malnutrition in Asian countries, and plants that can survive extreme weather conditions • Other possible crops include bananas with vaccines for diseases like hepatitis B and plants that produce biodegradable plastics • Ex. of transgenic bacteria: • Produce insulin, growth hormones, and substances that dissolve blood clots • Can slow the formation of ice crystals on crops to protect them from frost damage, clean up oil spills more efficiently, and decompose garbage • Human genome project (HGP) • Completed in 2003 • Goal was to determine the sequence of the approximately three billion nucleotides that make up human DNA and to identify all of the human genes • How done? • Each of the 46 chromosomes was cleaved • Several restriction enzymes were used to produce fragments with overlapping sequences • Fragments were combined with vectors to create recombinant DNA • Recombinant DNA was cloned to make many copies, then sequenced with machines • Computers analyzed the overlapping regions to generate one continuous sequence • After HGP was done, they discovered that less than 2% of all of the nucleotides in the human genome code for all of the proteins in the body – same amongst all humans • Genome is filled with long stretches of repeated sequences that have no direct function – called noncoding sequences – makes each of us unique. • Gel electrophoresis – an electric current is used to separate DNA fragments according to the size of the fragments Video • DNA is loaded on the negatively charged end of a gel • An electric current is applied • DNA fragments move toward the positive end of the gel • Smaller fragments move faster • Unique pattern is created • Can be used for identification; to study DNA fragments of various sizes • Portions of the gel containing each band can be removed and studied • DNA fingerprinting – involves separating the noncoding sequences using gel electrophoresis in order to observe the distinct banding patterns that are unique to every individual • Can be used by forensic scientists to identify suspects and victims in criminal cases, to determine paternity, to identify soldiers killed in war, and to free innocent people who have been wrongfully accused • Gene therapy • A technique to correct mutated genes that cause human disease • Done by inserting a normal gene into a viral vector. Target cells in the patient are infected with the virus, and the recombinant DNA material is released into the affected cells • Once in the cells, the normal gene inserts itself into the genome and begins functioning • Recent trials involve diabetes, cancer, retinal disease, and Parkinson’s • Stem cell research: • Some cells in the body can give rise to ANY tissue type (totipotent) • Some cells can only give rise to a few tissue types (multipotent) • Totipotent cells may be used to regrow lost limbs, regenerate nerve cells, or produce important chemicals for humans (such as insulin) • Source of stem cells is often human embryos – controversial • Cloning: making 2 organisms with identical DNA • How done? • Egg cell is taken from a female donor • Chromosomes are removed from the donor egg so the egg has no DNA • Cells taken from donor whose DNA is to be cloned – given chemicals to forget their specialized roles • Donor cell is fused with egg cell • Egg cell is implanted into a female carrier • Egg develops into an embryo that has the same DNA as the donor • Possible uses for cloning: • Cloning transgenic animals for medical study • Cloning stem cells for research • Reviving extinct or endangered organisms • Cloning organs for transplant • Human cloning could even be possible…yet is very controversial