3Biotechnology Products The use of technology to alter the genomes of viruses, bacteria, and other cells for medical or industrial purposes is called genetic engineering.
4Biotechnology Products Organisms that have had a foreign gene inserted into them are called transgenic organisms. (TRANSferred GENE = TRANS GENIC)
5DNA technology is changing the pharmaceutical industry and medicine Therapeutic Hormones Consider human insulin and human growth hormone (HGH).In the United States alone, about 2 million people with diabetes depend on insulin treatment.Before 1982, the main sources of this hormone were pig and cattle tissues obtained from slaughterhouses.Insulin extracted from these animals is chemically similar, but not identical, to human insulin, and it causes harmful side effects in some people.
6DNA technology is changing the pharmaceutical industry and medicine Genetic engineering has largely solved this problem by developing bacteria that synthesize and secrete actual human insulin.In 1982, Human growth hormone was urgently needed. In 1985, molecular biologists were able to produce HGH in bacteria.Before this genetically engineered hormone became available, children with a HGH deficiency had to rely on scarce supplies from human cadavers or else face dwarfism.
7Human insulin produced by bacteria Human insulin produced by bacteriaIn 1982, Humulin became the first recombinant drug approved by the Food and Drug AdministrationFigure 12.7A
9Biotechnology Products From Bacteria Recombinant DNA technology means to recombine the DNA of an organism to make it more useful to humans.It is used to produce bacteria that reproduce in large vats to get them to make a large amount of a particular protein, such as insulin, growth hormone, clotting proteins for hemophiliacs, and hepatitis B vaccine.
11VaccinesDNA technology is also helping medical researchers develop vaccines.A vaccine is a harmless variant or derivative of a pathogen (usually a bacterium or virus) that is used to prevent an infectious disease.When a person is inoculated, the vaccine stimulates the immune system to develop lasting defenses against the pathogen.For the many viral diseases for which there is no effective drug treatment, prevention by vaccination is virtually the only medical way to prevent illness.
12Vaccines One DNA technology vaccine is for the hepatitis B virus. Hepatitis is a disabling and sometimes fatal liver disease, and the hepatitis B virus may also cause liver cancer.
13VaccinesSmallpox was once a dreaded human disease, but it was eradicated worldwide in the 1970s by widespread vaccination with a harmless variant of the smallpox virus.In fact, the harmless virus could be engineered to carry the genes needed to vaccinate against several diseases simultaneously.In the future, one inoculation may prevent a dozen diseases.
15Biotechnology Products From Bacteria Transgenic bacteria can also help plants. For example, bacteria that live in plants have genes spliced in that let them resist insect toxins; this protects the roots of the plants, too.
16Biotechnology Products From Bacteria Bacteria can be genetically engineered to degrade a particular substance, for instance, transgenic bacteria have been produced which have the ability to eat oil after an oil spill.Biotechnology Products From Bacteria
17Biotechnology Products From Bacteria Industry has found that bacteria can be used as filters to prevent airborne chemicals from being vented into the air.They can also remove sulfur from coal before it is burned and help clean up toxic dumps.Furthermore, these bacteria were given “suicide” genes that caused them to self-destruct when the job is accomplished.
18Biotechnology Products From Bacteria Many major mining companies already use bacteria obtain various metals.Genetic engineering may enhance ability of bacteria to extract copper, uranium, and gold.
19Biotechnology Products From Plants Plants can also be genetically engineered to make cotton, corn, soybeans, and potatoes resistant to pests because their cells now produce an insect toxin.
20Biotechnology Products From Plants Plants are also being engineered to produce human hormones, clotting factors, and antibodies, in their seeds.One type of antibody made by corn can deliver a substance that kills tumor cells, and another made by soybeans can be used as treatment for genital herpes.
21Genetically modified organisms are transforming agriculture Scientists concerned with feeding the growing human population are using DNA technology to make genetically modified (GM) organisms for use in agriculture.A GM organism (Or GMO) is one that has acquired one or more genes by artificial means rather than by traditional breeding methods. (The new gene may or may not be from another species.)
22Genetically modified organisms are transforming agriculture To make genetically modified plants, researchers can manipulate the DNA of a single cell and then grow a plant with a new trait from the engineered cell.Already in commercial use are a number of crop plants carrying new genes for desirable traits, such as delayed ripening and resistance to spoilage and disease.
23Genetically modified organisms are transforming agriculture The most common vector used to introduce new genes into plant cells is a piece of DNA from a soil bacterium.With the help of a special enzyme, the gene for the desired trait is inserted into a plant cell, where it is integrated into a plant chromosome.Finally, the recombinant cell is cultured and grows into a whole plant.If the newly acquired gene is from another species, the recombinant organism is called a transgenic organism.
25Genetically modified organisms are transforming agriculture Genetic engineering is rapidly replacing traditional plant-breeding programs.For example, the majority of the American soybean and cotton crops are genetically modified.Many of these GM plants have received bacterial genes that make the plants resistant to herbicides or pests.Farmers can more easily grow these crops with far less tillage and reduced use of chemical insecticides.
26Genetically modified organisms are transforming agriculture Genetic engineering also has great potential for improving the nutritional value of crop plants.“Golden rice,” a transgenic variety with a few daffodil genes, produces grains containing beta-carotene, which our body uses to make vitamin A.This rice could help prevent vitamin A deficiency—and resulting blindness—among the half of the world’s people who depend on rice as their staple food.
27Colored Cotton Discovery Channel Video Clip On your textbook CD Chapter 32At the bottom of the page“EXTEND YOUR KNOWLEDGE”
28Biotechnology Products From Animals Agricultural researchers are also making transgenic animals. To do this, scientists first remove egg cells from a female and fertilize them in vitro. They then inject a previously cloned gene directly into the nuclei of the fertilized eggs. Some of the cells integrate the foreign DNA into their genomes. The engineered embryos are then surgically implanted in a surrogate mother. If an embryo develops successfully, the result is a transgenic animal, containing a gene from a third “parent” that may even be of another species.
29Biotechnology Products From Animals The procedure has been used to produce larger fish, cows, pigs, rabbits, and sheep.Genetically engineered fishes are now being kept in ponds that offer no escape to the wild because there is much concern that they will upset or destroy natural ecosystems.
31Biotechnology Products From Animals The goals of creating a transgenic animal are often the same as the goals of traditional breeding—for instance, to make a sheep with better quality wool or a cow that will mature in a shorter time. Scientists might, for example, identify and clone a gene that causes the development of larger muscles (muscles make up most of the meat we eat) in one variety of cattle and transfer it to other cattle or even to sheep.
32Biotechnology Products From Animals Transgenic animals also have been engineered to be pharmaceutical “factories” that produce otherwise rare biological substance for medical use. Recently, researchers have engineered transgenic chickens that express large amounts of the foreign product in their eggs. This success suggests that transgenic chickens may emerge as relatively inexpensive pharmaceutical factories in the near future.
33Biotechnology Products From Animals Gene pharming is the use of transgenic farm animals to produce therapeutic drugs in the animal’s milk.There are plans to produce drugs for the treatment of cystic fibrosis, cancer, blood diseases, and other disorders.An anti-clotting medicine is currently being produced by a herd of goats.
35Biotechnology Products From Animals Animals have been engineered to produce growth hormone in their urine instead of in milk.Urine is preferable to milk because only females produce milk, and not until maturity, but all animals produce urine from birth.
36XenotransplantationScientists have begun the process of genetically engineering animals to serve as organ donors for humans who need a transplant.We now have the ability to transplant kidneys, heart, liver, pancreas, lung, and other organs.
37XenotransplantationUnfortunately, however, there are not enough human donors to go around.Fifty thousand Americans need transplants a year, but only 20,000 patients get them.As many as 4,000 die a year while waiting for an organ.
38XenotransplantationYou might think that apes, such as the chimpanzee or the baboon might be a scientifically suitable species for this purpose.But apes are slow breeders and many people object to using apes for this purpose.
39XenotransplantationIn contrast, pigs have been an acceptable meat source, and a female pig can become pregnant at six months and can have two litters a year, each averaging about ten offspring.Ordinarily, the human body rejects transplanted pig organs.Genetic engineering, however, can make pig organs good for transplantation at less of a rejection risk.
40Cloning of AnimalsImagine that an animal has been genetically altered to serve as an organ donor.What would be the best possible way to get identical copies of this animal?
42Cloning of AnimalsIf cloning of the animal was possible, you could get many exact copies of this animal.Cloning is a form of asexual reproduction (without sex) because it requires only the genes of that one animal.
43Cloning of AnimalsIn 1997, scientists at the Raslin institute in Scotland announced that they produced a cloned sheep called Dolly.In 1998, genetically altered calves were cloned in the United States using the same method.
47Could GM organisms harm human health or the environment? As soon as scientists realized the power of DNA technology, they began to worry about potential dangers.Early concerns focused on the possibility that recombinant DNA technology might create new pathogens.What might happen, for instance, it cancer cell genes were transferred into bacteria or viruses?
48Could GM organisms harm human health or the environment? To guard against such rogue microbes, scientists developed a set of guidelines that were adopted as formal government regulations in the United States and some other countries.One safety measure is a set of strict laboratory procedures designed to protect researchers from infection by engineered microbes and to prevent the microbes from accidentally leaving the laboratory.In addition, strains of microorganisms to be used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside the laboratory.Finally, certain obviously dangerous experiments have been banned.
49Could GM organisms harm human health or the environment? Today, most public concern about possible hazards centers not on recombinant microbes but on genetically modified (GM) crop plants.Advocates of a cautious approach fear that some crops carrying genes from other species might cause allergies in humans or create super-weeds that are hazardous to the environment.
50Could GM organisms harm human health or the environment? Today, governments and regulatory agencies throughout the world are grappling with how to facilitate the use of biotechnology in agriculture, industry, and medicine while ensuring that new products and procedures are safe.In the United States, all projects are evaluated for potential risks by regulatory agencies such as the Food and Drug Administration, Environmental Protection Agency, National Institutes of Health, and Department of Agriculture.These agencies are under increasing pressure from some consumer groups.
51The Human Genome Project The Human Genome Project was a massive effort to put all of the genes in human chromosomes into the proper sequence. This was just finished in 2003.Project goals were to identify all the 25,000 genes in human DNA and determine the sequences of the 3 billion amino acids that make up human DNA.This allows scientists to detect some defective genes and tailor a treatment plan to the individual.
53Gene TherapyGene therapy gives a patient a normal gene to make up for a faulty gene.For example, there is a genetic disease of the liver that causes it to malfunction and leads to high levels of blood cholesterol, which makes the patient subject to fatal heart attacks at a young age.The person is injected with a virus that contains the normal gene.
54Gene TherapyAnother example is when fat enzymes are coated with the missing gene to cure cystic fibrosis and then sprayed into patients’ nostrils.Anti-cancer genes can also be injected directly into cancerous tumors.Perhaps it will be possible also to use gene therapy to cure hemophilia, diabetes, Parkinson disease, or AIDS.
55Diagnosis and Treatment of Disease DNA technology is being used increasingly in disease diagnosis.It is used to determine which genes are associated with genetic diseases.An individual’s gene expression profile may someday allow physicians to tailor treatments for many different disorders.
57DNA technology is used in courts of law DNA technology plays an important role in forensic science, the scientific analysis of evidence for crime scene and other legal investigations.In violent crimes, body fluids or small pieces of tissue may be left at the crime scene or on the clothes of the victim or assailant; if rape has occurred, semen may be recovered from the victim’s body.With enough tissue or semen, forensic scientists can determine the blood type or tissue type using older methods that test for proteins.However, such tests require fresh samples in relative large amounts.Also, because many people have the same blood or tissue type, this approach can only exclude a suspect; it cannot provide strong evidence of guilt.
58DNA technology is used in courts of law DNA testing, on the other hand, can identify the guilty individual with a high degree of certainty because the DNA sequence of every person is unique (except for identical twins).DNA testing requires only about 1,000 cells.In a murder case, for example, such analysis can be used to compare DNA samples from the suspect, the victim, and bloodstains on the suspect’s clothes.They provide a DNA fingerprint, or specific pattern of bands.
59DNA technology is used in courts of law DNA fingerprinting can also be used to establish family relationships.A comparison of the DNA of a mother, her child, and the purported father can conclusively settle a question of paternity.Sometimes paternity is of historical interest: DNA fingerprinting provided strong evidence that Thomas Jefferson or one of his close male relatives fathered at least one child with his slave Sally Hemings.
60DNA technology is used in courts of law Just how reliable is DNA fingerprinting?In most legal cases, the probability of two people having identical DNA fingerprints is between one chance in 100,000 and one in a billion.For this reason, DNA fingerprints are now accepted as compelling evidence by legal experts and scientists alike.In fact, DNA analysis on stored forensic samples has provided the evidence needed to solve many “cold cases” in recent years.DNA fingerprinting has also exonerated many wrongly convicted people, some of whom were on death row.
61DNA Fingerprinting and the Criminal Justice System: Discussion Figure 12.12BDefendant’sbloodBlood fromdefendant’s clothesVictim’sFigure 12.12A