Biotechnology Chapter 6
Dec 22, 2015
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 disease-causing 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
2 The same restriction enzymes cut the same base sequences in plasmid DNA. 5 Recombinant DNA
inserted into host cells is copied each time the host cells divide.
p. 104
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.
3 The plasmid DNA and the human DNA fragments are mixed in a solution with enzymes that link them together.
Stepped Art
Recombinant DNA Technology
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
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
Fig. 6-1, p. 106
1 The foreign gene is transferred into a plant cell. It becomes incorporated into one of the plant’s chromosomes.
2 The plant cell divides to form an embryo that develops into a mature transgenic plant as shown below.
Embryo
Chromosomes inside plant cell nucleus
Bacterial chromosome with foreign gene inserted
Stepped Art
How Transgenic Plants Are Made
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
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
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)