biotechnology 1. on november 22, 1983, the sleepy english village of narborough awoke to news of a...

BIOTECHNOLOGYBIOTECHNOLOGY

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On November 22, 1983, the sleepy English village of Narborough awoke to news of a horrific crime: A 15-year-old-girl named Lynda Mann had been raped and murdered on a country lane near her home. The killer left behind few clues, except for semen on the victim’s body and clothes. Despite extensive investigation, the trail of evidence ran cold and the crime went unsolved.

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Three years later, the horror resurfaced when another 15-year old girl, Dawn Ashworth, was also raped and murdered less than a mile away from the first crime scene. When tests indicated that the 1983 and 1986 semen samples could be from the same man, police began to search for a double murderer. After another extensive investigation, a maintenance worker from a nearby hospital was arrested and charged with both crimes. Under considerable pressure from police, the worker confessed to the second murder, but denied committing the first.

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DNA TechnologyDNA Technology

In an attempt to pin both murders on the suspect, investigators turned to Alec Jeffreys, a professor at nearby Leicester University, who had recently developed the first DNA fingerprint identification system. Because the DNA sequence of every person unique (except for identical twins), DNA fingerprinting can be used to determine with near certainty whether two samples of genetic material are from the same individual. Jeffreys compared DNA from the 1983 and 1986 semen samples. As the police suspected, the DNA analysis proved that the same person had committed both crimes. However, when Jeffreys analyzed the suspect’s DNA, it did not match either crime scene sample, proving that the suspect must be innocent. The police quickly released the suspect, making him the first person in legal history to be exonerated by DNA evidence.

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The detectives were back at square one. In an attempt to collect more evidence, they asked every young male from the surrounding area to donate blood for DNA testing. Although 5,000 men were sampled, none had DNA that matched the evidence from the crime scenes. The police were once again stymied. The case finally broke when a pub-goer described how a man named Cohn Pitchfork had bullied him into submitting blood on Pitchfork’s behalf. The police promptly ar rested Pitchfork and took a sample of his blood. Indeed, his DNA matched the samples from the two crime scenes. Cohn Pitchfork pleaded guilty to both crimes, closing the first murder case ever to be solved by DNA evidence.

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The Narborough murders were the first of many criminal in vestigations that have relied on DNA evidence. DNA technology— methods for studying and manipulating genetic material—have rapidly revolutionized the field of forensics, the scientific analy sis of evidence for legal investigations. Since its introduction, DNA fingerprinting has become a standard law enforcement tool and has provided crucial evidence (of both innocence and guilt) in many famous cases, including the O.J. Simpson mur der trial and the impeachment of President Bill Clinton. As we will see, DNA technology has applications in many other fields, from cancer research to agriculture and even history. Perhaps the most exciting use of DNA technology in basic research is the Human Genome Project, whose goal was to map the entire human DNA down to the level of its nucleotide sequences. This project is expected to help us better understand and treat many diseases.

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There are several significant roles that DNA technology has assumed in society, including gene cloning to produce useful products, DNA fingerprinting and forensic sci ence, human gene therapy for the treatment of disease, compar isons of genomes from different organisms, and the agricultural production of genetically modified organisms. There are also some of the social, legal, and ethical issues that are raised by these new technologies.

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Biotechnology ProductsBiotechnology Products

The use of technology to alter the genomes of viruses, bacteria, and other cells for medical or industrial purposes is called genetic engineering.

These days, bacteria, plants, and animals are genetically engi neered to produce biotechnology products.

Organisms that have had a foreign gene inserted into them are called trans genic organisms. (TRANSferred GENE = TRANS GENIC).

DNA technology is changing the pharmaceutical industry and medicine

DNA technology, and gene cloning in particular, is widely used to produce medicines and to diagnose diseases.

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DNA technology is changing the DNA technology is changing the pharmaceutical industry and pharmaceutical industry and medicinemedicineTherapeutic 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.

DNA technology is changing the DNA technology is changing the pharmaceutical industry and pharmaceutical industry and medicinemedicineGenetic engineering has largely solved this

problem by developing bacteria that synthesize and secrete actual human insulin.

In 1982, because growth hormones from other animals are not effective in hu mans, HGH 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.

Human insulin produced by bacteria◦ In 1982, Humulin became the first

recombinant drug approved by the Food and Drug Administration

Figure 12.7A

Table 12.6

From BacteriaFrom 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 hor mone, clotting proteins for hemophiliacs, and hepatitis B vaccine.

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Hepatitis B VaccineHepatitis B Vaccine

VaccinesVaccines

DNA 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.

VaccinesVaccines

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.

VaccinesVaccines

Smallpox 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.

‘Reverse' vaccine may help combat Type 1 diabetes

The new Reverse Vaccine utilizes modified DNA to shut down specific sections of the immune system.

The vaccine has shown promising results in combatting Type 1 diabetes.

Most vaccines aim to boost a patient’s immune response to a virus by injecting a genetically modified version of the disease into the body. The Stanford vaccine does the opposite, intentionally turning off select portions of the immune response that are malfunctioning.

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Biotechnology Products From Biotechnology Products From BacteriaBacteriaTransgenic 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.

Biotechnology Biotechnology Products From Products From BacteriaBacteria

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.

From BacteriaFrom 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 cause them to self-destruct when the job is accomplished.

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Biotechnology Products From Biotechnology Products From BacteriaBacteriaMany major mining

companies already use bacteria to obtain various metals.

Genetic engineering may enhance ability of bacteria to extract copper, uranium, and gold.

Biotechnology Products From Biotechnology Products From PlantsPlants

Plants can also be genetically engineered to make cotton, corn, soybeans, and potatoes resistant to pests because their cells now produce an insect toxin.

Biotechnology Products From Biotechnology Products From PlantsPlants

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.

Genetically modified Genetically modified organisms are transforming organisms are transforming agricultureagricultureScientists 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.)

Genetically modified Genetically modified organisms are transforming organisms are transforming agricultureagricultureTo 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.

Genetically modified Genetically modified organisms are transforming organisms are transforming agricultureagriculture 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 re combinant 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.

Genetically modified Genetically modified organisms are transforming organisms are transforming agricultureagricultureGenetic 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.

Genetically modified Genetically modified organisms are transforming organisms are transforming agricultureagricultureGenetic 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.

Biotechnology Products From Biotechnology Products From AnimalsAnimals

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.

From AnimalsFrom Animals

Techniques have been developed to insert genes into the eggs of 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.

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Transgenic PigTransgenic Pig


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 ma ture in a shorter time. Scientists might, for example, identify and clone a gene that causes the development of larger mus cles (muscles make up most of the meat we eat) in one vari ety of cattle and transfer it to other cattle or even to sheep.


Transgenic animals also have been engineered to be phar maceutical “factories” that produce otherwise rare biological substances 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 facto ries in the near future.


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.

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Pharm AnimalsPharm 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.

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XenotransplantationXenotransplantation

Scientists 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.

Unfortunately, however, there are not enough human donors to go round.

Fifty thousand Americans need transplants a year, but only 20,000 patients get them. As many as 4,000 die each year while waiting for an organ.

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XenotransplantationXenotransplantation

You 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.

In 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.

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Cloning of AnimalsCloning of Animals

Imagine that an animal has been genetically altered to serve as an organ donor. What would be the best possible way to get identi cal copies of this animal?

If cloning of the animal was possible, you could get many exact copies of this animal.

Cloning is a form of asexual re production (without sex) because it requires only the genes of that one animal.

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CloningCloning

Cloning of AnimalsCloning of Animals

In 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.

CLONING VIDEO

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ClonesClones

Clone?Clone?

Could GM organisms harm human Could GM organisms harm human health or the environment?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, if cancer cell genes were transferred into bacteria or viruses?


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.


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.


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.

The Human Genome ProjectThe Human Genome Project

The Human Genome Project was a massive effort to figure out what the sequence is of all of the genes in human chromosomes. 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 nucleic acids that make up human DNA.

This allows scientists to detect some defective genes and tailor a treatment plan to the individual.

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The Human Genome ProjectThe Human Genome Project

Gene TherapyGene Therapy

Gene 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.

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Gene TherapyGene Therapy

Another 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.

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Diagnosis and Treatment of Diagnosis and Treatment of DiseaseDisease

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.

The Role of Recombinant DNA The Role of Recombinant DNA technology in Biotechnologytechnology in Biotechnology

Recombinant DNA technology◦Intentionally modifying genomes of organisms

for practical purposes◦Three goals

Eliminate undesirable phenotypic traits Combine beneficial traits of two or more

organisms Create organisms that synthesize products

humans need

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Overview of Overview of recombinant DNA recombinant DNA technologytechnology

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Figure 8.1

The Tools of Recombinant DNA The Tools of Recombinant DNA TechnologyTechnology

Mutagens◦Physical and chemical agents that produce

mutations◦Scientists utilize mutagens to

◦Create changes in microbes’ genomes to change phenotypes

◦Select for and culture cells with beneficial characteristics

◦Mutated genes alone can be isolated

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Natural Mutation in Fruit FlyNatural Mutation in Fruit Fly


The Use of Reverse Transcriptase to Synthesize cDNA◦Isolated from retroviruses◦Uses RNA template to transcribe molecule of

DNA◦Easier to isolate mRNA molecule for desired

protein first Allows cloning in prokaryotic cells

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Synthetic Nucleic Acids◦Molecules of DNA and RNA produced in cell-free

solutions◦Uses of synthetic nucleic acids

Elucidating the genetic code Creating genes for specific proteins Synthesizing DNA and RNA probes to locate

specific sequences of nucleotides Synthesizing antisense nucleic acid molecules

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Restriction Enzymes◦Bacterial enzymes that cut DNA molecules only

at restriction sites◦One enzyme might only cleave T-T apart;

another enzyme only cleaves A-T apart, etc.◦We use one enzyme, and see how many pieces

result. Then we use the next enzyme, etc. That shows us the sequence of DNA in a sample.

◦Restriction Enzymes video

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Actions of Actions of restriction restriction enzymesenzymes

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Figure 8.2


Vectors◦Nucleic acid molecules that deliver a gene into

a cell◦Useful properties

Small enough to manipulate in a lab Survive inside cells Contain recognizable genetic marker Ensure genetic expression of gene

◦Include viral genomes, transposons, and plasmids

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Gene Libraries◦A collection of bacterial or phage clones

Each clone in library often contains one gene of an organism’s genome

◦Library may contain all genes of a single chromosome

◦Library may contain set of DNA complementary to mRNA

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Techniques of Recombinant DNA Techniques of Recombinant DNA TechnologyTechnology

Multiplying DNA in vitro: The Polymerase Chain Reaction (PCR)

VIDEO CLIP◦Large number of identical molecules of DNA

produced in vitro◦Critical to amplify DNA in variety of situations

Epidemiologists use to amplify genome of unknown pathogen

Amplified DNA from Bacillus anthracis spores in 2001 to identify source of spores

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Multiplying DNA in vitro: The Polymerase Chain Reaction (PCR)◦Repetitive process consisting of three steps

Denaturation Priming Extension

◦Can be automated using a thermocycler

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Polymerase Polymerase chain chain reaction reaction (PCR)(PCR)

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Figure 8.5a

Polymerase Polymerase chain chain reaction reaction (PCR)(PCR)

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Figure 8.5b


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Separating DNA Molecules: Gel Electrophoresis and the Southern Blot◦Gel electrophoresis

Separates molecules based on electrical charge, size, and shape

Allows scientists to isolate DNA of interest Negatively charged DNA drawn toward positive electrode Agarose makes up gel; acts as molecular sieve Smaller fragments migrate faster and farther than larger

ones Determine size by comparing distance migrated to

standards

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Gel electrophoresisGel electrophoresis

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Figure 8.6

GEL ELECTROPHORESIS VIDEO

Video of our lab’s gel electrophoresisElectrophoresis Results video

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Separating DNA Molecules: Gel Electrophoresis and the Southern Blot◦Southern blot

DNA transferred from gel to nitrocellulose membrane

Probes used to localize DNA sequence of interest Northern blot – used to detect RNA

◦Uses of Southern blots Genetic “fingerprinting” Diagnosis of infectious disease Demonstrate incidence and prevalence of

organisms that cannot be cultured

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The Southern The Southern blot blot techniquetechnique

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Figure 8.7


DNA Microarrays◦MICROARRAY VIDEO◦Consist of molecules of immobilized single-

stranded DNA◦Fluorescently labeled DNA washed over array

will adhere only at locations where there are complementary DNA sequences

◦Variety of scientific uses of DNA microarrays Monitoring gene expression Diagnosis of infection Identification of organisms in an environmental

sample

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DNA microarrayDNA microarray

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Figure 8.8


Inserting DNA into Cells◦Goal of DNA technology is insertion of DNA into

cell ◦Natural methods

Transformation Transduction Conjugation

◦Artificial methods Electroporation Protoplast fusion Injection – gene gun and microinjection

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TransformationTransformation

Transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous DNA from its surroundings. Transformation occurs naturally in some species of bacteria, but it can also be caused artificially.

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TransductionTransduction

Transduction is when DNA is transferred from one bacterium to another by a virus

The virus is called a bacteriophage.

Conjugation is when a bacterium uses its sex pilus to transfer some of its DNA to another bacterium.

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Artificial methods of inserting DNA into Artificial methods of inserting DNA into cellscells

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Figure 8.9a/b

Artificial methods of inserting DNA into Artificial methods of inserting DNA into cellscells

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Figure 8.9c/d

Applications of Recombinant DNA Applications of Recombinant DNA TechnologyTechnology

Genetic Mapping◦Locating genes on a nucleic acid molecule◦Provides useful facts concerning metabolism,

growth characteristics, and relatedness to others

Locating Genes◦Until 1970, genes identified by labor-intensive

methods◦Simpler and universal methods now available◦Restriction fragmentation◦Fluorescent in situ hybridization (FISH)

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Fluorescent in situ hybridizationFluorescent in situ hybridization

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Figure 8.10

Used to detect and localize the presence or absence of specific DNA sequences on chromosomes.

Also allows for more precise DNA karyotyping.

Automated DNA sequencingAutomated DNA sequencing88

Figure 8.11


Environmental Studies◦Most microorganisms have never been grown in

a laboratory◦Scientists know them only by their DNA

fingerprints Allowed identification of over 500 species of

bacteria from human mouths Determined that methane-producing archaea are

a problem in rice agriculture

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Pharmaceutical and Therapeutic Applications◦Protein synthesis

Creation of synthetic peptides for cloning◦Vaccines

Production of safer vaccines Introduce genes of pathogens into common fruits and

vegetables Injecting humans with plasmid carrying gene from pathogen

◦Humans synthesize pathogen’s proteins

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Pharmaceutical and Therapeutic Applications◦Genetic screening

DNA microarrays used to screen individuals for inherited disease caused by mutations

Can also identify pathogen’s DNA in blood or tissues

◦DNA fingerprinting Identifying individuals or organisms by their

unique DNA sequence

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Pharmaceutical and Therapeutic Applications◦Gene therapy

Missing or defective genes replaced with normal copies

Some patients’ immune systems react negatively◦Medical diagnosis

Patient specimens can be examined for presence of gene sequences unique to certain pathogens

◦Xenotransplants Animal cells, tissues, or organs introduced into

human body

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DNA DNA fingerprintingfingerprinting

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Figure 8.12

DNA FINGERPRINT VIDEO

http://www.biotechnologyonline.gov.au/popups/int_dnaprofiling.html

http://www.biotechnologyonline.gov.au/popups/int_dnaprofiling.html

DNA technology is used in courts of law

DNA technology plays an important role in forensic science, the scien tific analysis of evidence for crime scene and other legal in vestigations. 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 recov ered 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, be cause many people have the same blood or tissue type, this approach can only exclude a suspect; it cannot provide strong evidence of guilt.

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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.

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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 Jeffer son or one of his close male relatives fathered at least one child with his slave Sally Hemings.

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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.

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DNA Fingerprinting and the Criminal Justice System

Traditional fingerprinting has been used for years to identify criminals and to exonerate those wrongly accused of crimes. The opportunity now arises to use DNA fingerprinting in the same way. DNA fingerprinting requires only a small DNA sample. This sample can come from blood left at the scene of a crime, semen from a rape case, even a single hair root!

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The DNA is amplified, cut with restriction enzymes, and separated by gel electrophoresis to produce a unique DNA fragment pattern. The same procedure is done several times with restriction enzymes, making it nearly impossible for anyone else in the world would have the same set of patterns. Advocates of DNA fingerprinting claim that identification is beyond a reasonable doubt.

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Opponents of this technology, however, point out that it is not without its problems. Police or laboratory negligence can invalidate the evidence. For example, during the O.J. Simpson trial, the defense claimed that the DNA evidence was inadmissible because it could not be proven that the police had not planted O. J's blood at the crime scene. There have also been reported problems with sloppy laboratory procedures and the credibility of forensic experts. In addition to identifying criminals, DNA fingerprinting can be used to establish paternity and maternity, determine nationality for immigration purposes, and identify victims of a national disaster, such as the terrorist attack of September 11, 2001.

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Considering the usefulness of DNA fingerprints, perhaps everyone should be required to contribute blood to create a national DNA fingerprint data bank. Some say however this would constitute an unreasonable search, which is unconstitutional.

Would you be willing to provide your DNA for a national DNA data bank? What types of privacy restrictions would you want on your DNA?

If not everyone, do you think that convicted felons at least should be required to provide DNA for a databank?

Should all defendants have access to DNA fingerprinting (at government expense) to prove that they did not do a crime? Should this include those already convicted of crimes who want to reopen their cases using new DNA evidence?

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Defendant’sblood

Blood fromdefendant’s clothes Victim’s

blood

Figure 12.12A Figure 12.12B


Agricultural Applications◦Production of transgenic organisms

Recombinant plants and animals altered by addition of genes from other organisms

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Agricultural Applications◦Herbicide resistance

Gene from Salmonella conveys resistance to glyphosate (Roundup)◦Farmers can kill weeds without killing crops

◦Salt tolerance Scientists have removed gene for salt tolerance

and inserted into tomato and canola plants Transgenic plants survive, produce fruit, and

remove salt from soil

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Agricultural Applications◦Freeze resistance

Crops sprayed with genetically modified bacteria can tolerate mild freezes

◦Pest resistance Bt toxin

◦Naturally occurring toxin only harmful to insects ◦Organic farmers use it to reduce insect damage to crops

Gene for Bt toxin inserted into various crop plants Genes for Phytophthora resistance inserted into

potato crops

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Agricultural Applications◦Improvements in nutritional value and yield

Tomatoes allowed to ripen on vine and shelf life increased◦Gene for enzyme that breaks down pectin suppressed

BGH allows cattle to gain weight more rapidly, ◦Have meat with lower fat content and produce 10%

more milk Gene for β-carotene (vitamin A precursor) inserted

into rice Scientists considering transplanting genes coding

for entire metabolic pathways

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The Ethics and Safety of Recombinant The Ethics and Safety of Recombinant DNA TechnologyDNA Technology

Supremacist view – humans are of greater value than animals

Long-term effects of transgenic manipulations are unknown

Unforeseen problems arise from every new technology and procedure

Natural genetic transfer could deliver genes from transgenic plants and animals into other organisms

Transgenic organisms could trigger allergies or cause harmless organisms to become pathogenic

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Studies have not shown any risks to human health or environment

Standards imposed on labs involved in recombinant DNA technology

Can create biological weapons using same technology

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Ethical Issues◦Routine screenings?◦Who should pay?◦Genetic privacy rights?◦Profits from genetically altered organisms?◦Required genetic screening?◦Forced correction of “genetic abnormalities”?

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Are Genetically Engineered Foods Are Genetically Engineered Foods Safe?Safe?

Are Genetically Engineered Foods Safe?

A series of focus groups conducted by the Food and Drug Administration in 2000 showed that although most participants believed that genetically engineered foods might offer benefits, they also feared unknown long-term health consequences that might be associated with the technology. Some say that when it comes to human and environmental safety, there should be clear evidence of the absence of risks.

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The discovery that a genetically engineered corn called Star Link had inadvertently made it into the food supply triggered the recall of chocolate shells, tortillas, and many other corn-based foodstuffs from supermarkets.

Further, the makers of Star Link were forced to buy back Star Link from farmers and to compensate food producers at an estimated cost of several hundred million dollars.

Star Link is a type of corn that contains a foreign gene taken from a common soil bacterium whose insecticidal properties have long been known.

About a dozen varieties of this corn, as well as potatoes and one variety of tomato, have now been approved for human consumption.

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These strains contain a gene for an insecticidal protein. The makers of Star Link decided to use a gene for a related protein. They thought that using this molecule might slow down the chances of pest resistance to the genetically modified corn. In order to get FDA approval for use in foods, the makers of Star Link performed the required tasks. Like the other now approved strains, Star Link was not poisonous to rodents, and its biochemical structure is not similar to those of most food allergens. However, it resisted digestion and longer than the other genetically modified proteins when it was put in simulated stomach acid and subjected to heat. Because most food allergens are stable like this, Star Link was not approved for human consumption.

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The scientific community is now trying to devise more tests for allergens because it has not been possible to determine conclusively whether or not this second protein is an allergen. It is also unclear how resistant to digestion a protein must be in order to be an allergen, and it is also unclear what degree of sequence similarity a potential allergen must have two unknown allergy and to raise concern. Therefore, it is not understood yet where the thresholds are for sensitization to food allergens and thresholds for the visitation of a reaction with food allergens.

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Other scientists are concerned about the following potential drawbacks to planting this variety of genetically modified corn: resistance among populations of the target pest, exchange of genetic material between the transgenic crop and related plant species, and crops impact on non-target species. They feel that many more studies are needed before it can be said for certain that genetically modified corn has no ecological drawbacks.

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Despite controversies, the planting of genetically engineered corn increased in 2001. The USDA reports that US armors planted genetically engineered corn on 26% of all corn acres, 1% more than in 2000. In all, US farmers planted at least 72 million acres with mostly genetically engineered corn, soybeans, and cotton. The public wants all of genetically engineered foods to be labeled as such, but this may not be easy to accomplish because most corn meal is derived from both conventional and genetically engineered corn. So far, there has been no attempt to sort out one type of food product from the other.

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Genetic ProfilingGenetic Profiling

Genetic Profiling

Now that the human genome has been sequenced, researchers are using various means to discover which sequencing differences among people might forecast the possibility of a future disease. No doubt, there are benefits to genetic profiling. For example, knowledge of your genes might indicate your susceptibility to various types of cancer. This information could be used to develop a prevention program, including the avoidance of environmental influences associated with the disease. Also, you would be less inclined to smoke if you knew your genes make it almost inevitable that smoking will give you lung cancer. Are there any reasons not to be in favor of genetic profiling?

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Genetic Profiling

People, however, worry that insurance companies and employers could use their genetic profile against them. Perhaps employers will not higher, or insurance companies will not ensure, those who have a propensity for particular diseases. The federal government and about 25 states have passed laws prohibiting genetic discrimination by health insurers, and 11 have passed laws prohibiting genetic discrimination by employers. The legislation states that genetic information cannot be released to anyone without the subject’s permission. Is that such legislation enough to ally are fears of discrimination? Might an employer not hire you or an insurance company not ensure you simply because you will not grant permission to access your genetic profile?

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Genetic Profiling

Say that two women are being considered for the same position, and each meets all the basic requirements for the job. The first denies access to her genetic profile, while the second one grants permission to look at her genetic profile. Thinking that the first woman might have had something to hide, employer hires a second one. The possibility that sick days may be needed by the first woman makes the second woman a more cost-effective choice. People who have genetic profiles proving they are likely to be healthy in the future might even use them in order to have an advantage over those who have profile showing that they are likely to develop serious illnesses in the future. In this way, we might create a genetic underclass.

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Genetic Profiling

Genetic information is sometimes misunderstood, particularly by laypeople. In the past, for example, as an effort to combat sickle cell disease, many people were screened for it. Unfortunately, those who were found to have the sickle trait, and not the actual disease, experienced discrimination at school, or from employers and insurance carriers. It is possible misunderstanding of the results enough not to do genetic profiling, or do the potential benefits outweigh the risks?

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Genetic Profiling

On the other hand, employers may fear that the government might use genetic information one day to require them to provide an environment specific to every employee's need, in order to prevent future illness. Would you approve of this, or should individuals be required to leave an area or job that exposes them to an environmental influence that could be detrimental to their health?

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Genetic Profiling

Some people believe that free access to genetic profiling data is absolutely essential to developing better preventative care for all. If researchers can match genetic profiles to the environmental conditions that bring on illnesses, they could come up with better prevention guidelines for the next generation. Should genetic profiles and health records become public information under these circumstances? It would particularly help in the study of complex diseases, such as cardiovascular disorders, non-insulin-dependent diabetes, and juvenile rheumatoid arthritis. Perhaps there would be some way to protect privacy and still make the information known?

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If present legislation to protect privacy is inadequate, what can be done to truly keep such information private? Should the information be coded in some way, so that only the medical profession can read it? Should people be responsible for keeping the only copy of their profiles, which would be coded so that even they cannot read it? Or, do you believe that anyone should have access to anyone's profile, for whatever reason?

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Should people be encouraged or even required to have their DNA analyzed so that they can develop programs to possibly prevent future illness?

Should employers be encouraged or required to provide an environment suitable to a person's genetic profile? Or should the individual ovoid a work environment that could bring on an illness?

How come we balance individual rights with the public health benefits of matching genetic profiles to detrimental environments?

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Medicine’s Wild Kingdom Time Magazine

Potent chemicals derived from exotic animals are yielding a range of treatments.

One creature you don't want to stumble upon it in a dark forest is a hungry vampire bat. The 3 inch long, pointy eared night stalker has an anti-clotting substance and its saliva that allows it to dine on an unending flow of its victim’s blood. There is, however, one group of people that may come to see the vampire bats as lifesavers. They are stroke patients to desperately need improved clot-busting drugs that prevent brain damage and paralysis by restoring blood flow to stroke ravaged tissues.

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That's the idea behind a new drug that 15 US hospitals will soon begin testing. It's a synthetic copy of an enzyme bats secrete when they salivate over freshly bitten gray. Stroke experts are already buzzing because early studies in mice suggests patients may be able to safely receive the bat spit up to nine hours after they've had a stroke. The only clot-busting drug now on the market must be given within three hours.

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Medicine’s Wild KingdomMedicine’s Wild Kingdom


Bats are not the only scary animals that may someday contribute to the world's expanding medicine cabinet.

Scientists are studying everything from Gila monsters to scorpions to copperhead snakes.

The toxins these creatures use to kill their prey or ward off foes hold seemingly boundless potential to treat human diseases ranging from diabetes to brain cancer.

Refined through millions of years of evolution, these substances found in animal saliva, then um, and, in some internal organs homed in on targets such as nerve cells better than most chemical combination's scientists concoct. And often, they circulate in the body for hours on end.

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Still, turning Mother Nature’s toxins into life-saving drugs can be harder than killing a Python with a pebble.

First, researchers must isolate, analyze, and synthesize specific compounds in such a way that they can be tolerated by humans and mass produced.

The risk of failure is so high that many pharmaceutical companies shun poison derived experimental drugs until they are well past the developmental stage.

That leaves scientists dependent upon scarce venture capital and public funding.

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Scientists are also racing against a biological clock. Species identified to date may represent just 1/10 of the

biological diversity on earth. And potentially therapeutic creatures are vanishing at

unprecedented rates. Although the vampire bat is not endangered, 13 other bat

species are. The natural world is the largest pharmaceutical factory we

have, and a lot of potential benefit is being lost.

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Drugs like the synthesized bat spit can earn attractive returns.

An anticoagulant derived from leach saliva pulled in an estimated $38 million last year.

And a hypertension drug derived from the venom of the South American viper drew more than $1 billion in annual sales before the compounds became available in generic form in the mid-1990s.

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Many animal poisons have the ability to hit specific bull’s-eyes in the body.

One species of snail, for example, injects its prey with a poison that paralyzes nerve cells.

The tiny Ecuadorian Poison Dart Frog secretes a skin toxin that keeps predators at bay.

Both substances block pain signals to the brain and have led to experimental pain medications that could be as potent as morphine but with no risk of addiction.

The poison in puffer fish has also been found to ease the pain of heroin withdrawal and cancer.

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For sheer horror, nothing matches staining of the 8 inch giant yellow Israel scorpion.

It packs neurotoxins that can cause excruciating pain. Yet at least one of the hundreds of proteins involved in that

process also has the ability to seek out and find to a receptor that is abnormally expressed on the surface of brain tumor cells but not on normal selves.

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Last year, to cancer centers began testing a copy of the protein that was developed from this toxin.

The researchers compared the synthesized protein with a radioactive isotope and injected it into the brains of clinical trial patients suffering from a cancer called glioma.

In the brain, they believe, the drug travels straight to the tumors and kills them without damaging nearby healthy cells. It's like a guided missile.

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Exotic animals and their secretions don't necessarily have to be lethal to help humans.

One pharmaceutical company hopes to obtain food and drug administration approval for a diabetes drug derived from a hormone that Gila monsters secrete while munching on mice, bird eggs, and other favorite foods.

This substance mimics the human hormone that regulates insulin, which in turn controls blood sugar.

But unlike the human molecule, which is quickly degraded by enzymes in the body, the lizard version sticks around for hours.

And it helps the body regenerate insulin making cells. This can take us to new levels of blood sugar control.

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Despite the promise of animal-based drugs, the path from the rain forest to the FDA is rough with pitfalls.

For many companies, the biggest challenge has been figuring out how to develop and produce chemical copies of naturally occurring substances.

A professor at the University of Southern California School of medicine in has been developing a cancer drug based on the venom of the Southern copperhead snake.

With a shoestring budget from public grants, he managed to coax mammalian cells to make copies of the venom protein.

But it will be at least a year before a drug is ready for human testing.

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Emerging technologies should help speed the discovery and development of exotic drugs.

Computerized screening systems, for example, allow researchers to test experimental compounds against thousands of potential disease targets simultaneously.

That's important because science has barely scratched the surface of nature’s therapeutic potential.

There are 10 million organisms out there waging chemical warfare against each other; the abundance of possible drugs can not even be imagined.

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The problem is that many of these potential remedies are disappearing before they are even spotted.

Half of the world's plants and animals live in tropical forests, and most of these species are still unknown.

At the current rate of forest destruction, two thirds of land dwelling plant and animal species will be extinct by the end of this century.

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The urgency of preserving nature's bounty is not lost on patients like Duane Rualo. The 24-year-old accounting student at Cal State Long Beach was diagnosed with glioma in late 2001 and told he probably would not live long enough to make it to his fall 2003 graduation. After surgery and several shots of scorpion venom, his latest brain scan came up clear of cancer. His doctors can't say yet how important the scorpion has been to his recovery. But these days, Rualo pauses when he comes across a scorpion exhibit at a zoo. “I stop and think:’ Wow, they may have saved my life’”, he says. And who knows what other life-saving drugs may be lurking beyond the scorpions layer, the Gila monsters burrow, and the bats caves?

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New Cures on the HorizonNew Cures on the Horizon

New Cures on the Horizon

Now that we know the sequence of the bases in the DNA of all the human chromosomes, biologists all over the world believe this knowledge will result in rapid medical advances for ourselves and our children.

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First prediction: Many new medicines tailored to the individual will be available.

Most drugs are proteins or small chemicals that are able to interact with proteins. Today's drugs were usually discovered in a hit or miss fashion, but now researchers will be able to take a more systematic approach to finding effective medicines. In a recent search for a menace and that makes wounds heal, researchers cultured skin cells with 14 proteins that can cause skin cells to grow. Only one of these proteins actually made skin cells grow and did nothing else. They expect this protein to become an effective drug for conditions such as venous ulcers, which are skin lesions that affect many thousands of people in the United States. Tests leading to effective medicines can be carried out with many more proteins that scientists will discover by examining the human genome.

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Many drugs potentially have unwanted side effects. Why do some people and not others have won or more of the side effects?

Most likely, this is because people have different genetic profiles.

It is expected that a physician will be able to match patients to drugs that are safe or them on the basis of their genetic profiles.

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One study found that various combinations of mutations can lead to the development of asthma. A particular medicine, called albuterol, is effective and safe for patients with certain combinations of mutations and not others.

This example and others showed that many diseases are multi-factorial and that only a genetic profile is able to detect mutations are causing an individual to have a disease and how it should be properly treated.

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Second prediction: A longer and healthier life will be yours. Pre-embryonic gene therapy may become routine once we discovered

the genes that contribute to a longer and healthier lives. We know that the presence of three radicals causes cellular molecules to become unstable and cells to die. Certain genes are believed to code for antioxidant enzymes that detoxify free radicals.

It could be that human beings with particular forms of these genes have more efficient antioxidant enzymes, and therefore live longer. If so, researchers will no doubt be able to locate these genes and also others that promote a longer, healthier life. Perhaps certain genetic profiles allow some people to live far beyond the normal lifespan.

Researchers may be able to find which genes allow individuals to live a long time and to make them available to the general public. Then, many more people would live longer and healthier lives.

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Third prediction: You will be able to design your children.

Genome sequence data will be used to identify many more mutant genes that cause genetic disorders than are presently known.

In the future, it may be possible to cure genetic disorders before the child is born by adding a normal gene to any egg that carries a mutant gene.

Or an artificial chromosome, constructed to carry a large number of corrective genes, could automatically be placed in eggs.

In vitro fertilization would have to be utilized in order to take advantage of such measures for current genetic disorders before conception.

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Genome sequence data can also be used to identify genes for traits such as height, intelligence, or behavioral characteristics.

A couple could decide on their own which genes may wish to use to enhance a child's phenotype.

In other words, the sequencing of the human genome may bring about a genetically just society, in which all types of genes would be accessible to all parents.

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Finished!Congratulations!

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biotechnology 1. on november 22, 1983, the sleepy english village of narborough awoke to news of a...

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