Biotechnology by liaoqinmei

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									Biotechnology
DNA Technology
 Biotechnology Products

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

• Organisms that have had a
  foreign gene inserted into them
  are called transgenic organisms.
  (TRANSferred GENE = TRANS
  GENIC)
  DNA 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.
  DNA 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.
Human insulin produced by
bacteria
 – In 1982, Humulin became the first
   recombinant drug approved by the Food
   and Drug Administration




               Figure 12.7A
 Biotechnology 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.
Hepatitis B Vaccine
                 Vaccines
• 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.
            Vaccines
• 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.
              Vaccines
• 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.
 Biotechnology 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.
• Bacteria can be
  genetically engineered
  to degrade a
                           Biotechnology
  particular substance,       Products
  for instance,
  transgenic bacteria
                           From Bacteria
  have been produced
  which have the
  ability to eat oil
  after an oil spill.
 Biotechnology Products
      From Bacteria
• Industry has found that bacteria can he
  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.
 Biotechnology 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.
 Biotechnology 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.
  Biotechnology 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.
   Genetically 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.)
   Genetically 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.
   Genetically 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 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
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.
   Genetically 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.
         Colored Cotton
• Discovery Channel Video Clip
  – On your textbook CD
  – Chapter 32
  – At the bottom of the page
    • ―EXTEND YOUR KNOWLEDGE‖
  Biotechnology 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.
 Biotechnology 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.
Transgenic Pig
 Biotechnology 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 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.
 Biotechnology Products
      From Animals
• Transgenic animals also have been
  engineered to be phar-maceutical
  ―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
  facto-ries in the near future.
 Biotechnology 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.
Pharm Animals
 Biotechnology 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.
    Xenotransplantation

• 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.
     Xenotransplantation
• Unfortunately,
  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
  died that year while
  waiting for an organ.
    Xenotransplantation
• 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.
    Xenotransplantation
• 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.
     Cloning 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 identical copies of this animal?
Cloning
     Cloning of Animals
• 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.
     Cloning 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.
Clones
Clones
Clone?
Could 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?
 Could 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.
Could 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.
 Could 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.
The 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.
The Human Genome Project
          Gene 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.
          Gene 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.
Diagnosis 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.
Natural Mutation in Fruit Fly
  DNA 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.
 DNA 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.
 DNA 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.
  DNA 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.
    DNA Fingerprinting and the
     Criminal Justice System

                      Blood from
Defendant’s       defendant’s clothes   Victim’s
   blood                                 blood




              Figure 12.12A                        Figure 12.12B
    Are Genetically
Engineered Foods Safe?
Genetic Profiling
Medicine’s Wild Kingdom
New Cures on the Horizon

								
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