Biotechnology

Chapter 6

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

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

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

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

Guidelines1. Organisms be contained

2. Level of containment should match risk

3. Physical barriers should be used

4. Prohibited experiments risk too high

Video