Transcript 6.2 Recombinant DNA Technology

Chapter 6
Biotechnology
Central Points
 Recombinant DNA technology joins DNA
 Biotechnology uses recombinant DNA
technology to make products
 Bacteria, plants, and animals modified
 Safety of transgenic organisms debated
 Produce human proteins for disease treatment
 Many biotechnology inventions patented
Case A: A Taller Son for Chris
 Chris’ 10-year-old son, Mike, is short
 Want to treat him with human growth hormone
(hGH) produced by recombinant DNA technology
 If given before puberty, could help him grow
 Pediatrician does not recommend hGH treatment
6.1 What Is Biotechnology? Video
 Coupling of genetic technology to biological
systems
 Makes human proteins
 Previously, human proteins collected from many
sources: animals, cadavers, and donated blood
 Risk from these sources including death
In 1985, hGH Produced
 Potentially unlimited amounts of growth
hormone
 No possibility of contamination with diseasecausing agents
 Used to treat a number of serious growth
disorders
How Is hGH Produced?
 Recombinant DNA technology
 Transferred gene for hGH from a human cell
DNA to a bacterial cell
 Creating a transgenic organism
 Transgenic bacterial cell and its descendants
manufacture hGH
6.2 Recombinant DNA Technology:
Steps (1)
 DNA extracted from human cells
 DNA treated with restriction enzyme, cuts the
DNA at specific sites, produce “sticky end”
 Bacterial plasmid cut with same enzyme
 Plasmid functions as vector and carries human
DNA into bacterial cells
6.2 Recombinant DNA Technology:
Steps (2)
 Fragments of human DNA and plasmid mixed
together and join
 Plasmids enter the bacterial cells, copy
themselves, carry recombinant DNA into bacteria
 Bacteria express gene, synthesize the human
protein, can be used for treatments, vaccines, or
other purposes
Recombinant DNA Technology
1 Restriction
enzymes cut
specific base
sequences
everywhere
they occur
in human
chromosomes.
4 The result is recombinant DNA
molecules with both human and
plasmid DNA.
2 The same
restriction
enzymes cut
the same base
sequences in
plasmid DNA.
3 The plasmid
DNA and the
human DNA
fragments are
mixed in a
solution with
enzymes that link
them together.
5 Recombinant DNA
inserted into host
cells is copied each
time the host cells
divide.
Stepped Art
p. 104
Restriction Enzymes
 Restriction enzymes cut both DNA strands at a
recognition site, search for specific base
sequence
 > 1,000 different restriction enzymes
 Each cuts at specific and different recognition
sites
Restriction Enzymes
Animation: Action of restriction enzymes
Case A Questions
 After doctor’s visit, they decide
hGH not appropriate
 Should parents make all
medical decisions for children?
 Risks of hGH use and abuse
by athletes
Chromosomes inside
plant cell nucleus
1 The foreign gene is transferred into a
plant cell. It becomes incorporated into
one of the plant’s chromosomes.
Bacterial
chromosome
with foreign
gene inserted
How
Transgenic
Plants Are
Made
2 The plant cell divides to form an
embryo that develops into a mature
transgenic plant as shown below.
Embryo
Stepped Art
Fig. 6-1, p. 106
6.3 Other Transgenic Plants and Animals
 Production of medically important proteins
 Transgenic crops or genetically modified (GM),
plants with new characteristics
• Resistance to herbicides, insects, or viral or
fungal diseases
• Increase the nutritional value of crops
 Pigs for xenotransplants
Transgenic Crops
Transgenic Tobacco Produce hGH
Insulin from Recombinant DNA
Golden Rice
 Genes from daffodils and bacteria
 Produce beta carotene
Factor VIII
 Clotting factor for hemophiliacs
 Without the use of blood donors
Pigs for Possible Organ Transplant
 HLA transferred to pig embryos
Video: ABC News: Glow-in-the-dark pigs
Video: ABC News: Cloned Food
Approved
6.4 Are Transgenic Organisms Safe?
 Important to address by research and testing
• Health and environmental risks
• Economic and social issues
• Educate public
 Potential health risks
 Environmental risks, transfer of transgenes to
wild plants, and reduction in biodiversity
6.5 Studying Human Diseases
 Human Genome Project, plant and animal
genomes
 Many shared genes in other species, including
the mouse and Drosophila
 Animal models of human disease study drug
treatments and causes of disease
 Transgenic organisms used for models
Transgenic Animal Models
 Produce an animal with similar symptoms
 Used to study the development and progress of
a disease
 Used to develop and test drugs to cure or treat
animal model of the human disease
• Currently used for Huntington disease (HD)
 Eventually, drugs used to treat humans
Rhino Mouse
 Used to study immune deficiency conditions
Curly Tail Mouse
 Used to study neural tube defects
Obese Mouse
 Used to study weight-loss products
Case B: Strawberries on Trial
 Vandals destroyed strawberries treated with
transgenic “ice minus” bacteria
 Why did they do this? What were the risks and
benefits?
 Are transgenic organisms changing the course of
evolution?
 See the textbook for further questions on this case
6.6 Legal and Ethical Issues in
Biotechnology
 Patenting organisms and genes
 Diamond v. Chakrabarty
• Oil-eating bacteria used four plasmids from
different strains
• Produce one strain of Pseudomonas
 Harvard University patent on a transgenic
OncoMouse (U.S. only)
Issues of Patenting Transgenic Organisms
Spotlight on Ethics: Asilomar
Conference, 1975
 Potential hazards presented by recombinant DNA
technology
 Guidelines
1.
2.
3.
4.
Organisms be contained
Level of containment should match risk
Physical barriers should be used
Prohibited experiments risk too high
 Video