Manipulating the Genome
http://www.youtube.com/watch?v=jY-868_HDbs&feature=related
Genetic Engineering
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Direct human manipulation of an organism’s genetic material in a way that does not
occur under natural conditions
Two Tools:
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Plasmids (small circular pieces of DNA that can exit and enter bacterial cells)
Restriction Enzymes (chemical scissors that can cut DNA at specific sequences)
Recombinant DNA
 Fragment of DNA -> combining nucleotide sequences that would not normally be present
together in nature
 Two pieces that have been cut with the same restriction enzyme
Bacteria & Plants with New Characteristics
-pictureGenetic Engineering Examples:
Pictures and explanations
GFP:
 In 2008, Martin Chalfie, Osamu Shimomura, and Roger Y. Tsien were awarded the
Nobel Prize Chemistry for the discovery and development of GFP
 GFP stands for “green fluorescent protein” and refers to a protein isolated from jellyfish
(Aequorea victoria)
 GFP fluoresces green under blue light (this phenomenon is known as bioluminescence)
 The original GFP gene has been altered to fluoresce many other colours such as cyan,
blue, yellow, etc.
 The GFP gene can be artificially introduced into organisms and is often used as a reporter
of expression (only those cells in which the tagged gene is expressed, or the target
proteins are produced, will fluoresce when observed under fluorescence microscopy)
 GFP allows researchers to tag cells and follow their development, to study protein
trafficking and localization in living cells, to visualize events in structures within the
cells, track events in the body, and so on
 Alba, an albino fluorescent rabbit, was created using GFP for the purposes of art and
social commentary – “transgenic art”
 NeonPets, a US based company, markets green fluorescent mice to the pet industry as
NeonMice®
GloFish
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Produced by Yorktown Technologies, Glofish is the world’s first commercially available
transgenic animal that was originally bred to help detect environmental pollutants
Glofish are zebrafish that have had naturally occurring fluorescent proteins extracted
from jellyfish inserted into their DNA to make them glow red, green, or orange
They are the same as normal zebrafish in all aspects except that they are fluorescent
The technology was first pioneered by Zhiyuan Gong at the National University of
Singapore, and was developed while studying water pollutants
Glofish were created by inserting protein genes into zebrafish that would fluoresce in the
presence of certain contaminants to aid in the quick detection of polluted waterways
(pollution-detecting fish)
All subsequent Glofish were traditionally bred from the original transgenic zebrafish
once the fluorescence gene was integrated into its genome (this gene was passed onto all
offspring)
Scientists are hoping to develop a ‘switch’ that will cause Glofish (that always fluoresce
at the moment) to selectively fluoresce in the presence of environmental toxins
A non-fluorescing fish would signal that the water is safe, while a fluorescing fish would
signal that it is not
The sale of Glofish is illegal in California, Australia, Canada, and Europe due to concerns
about their safety and environmental effects
Spider Goat
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Developed by molecular biologist and University of Wyoming professor Randy Lewis
Strong, flexible spider silk is one of the most valuable materials in nature because it is
strong and very flexible (more durable than Kevlar, more stretchable than nylon, and
stronger than steel)
Spider silk can be used to make an array of products (artificial ligaments and tendons,
parachute cords, bulletproof vests, clothing, etc…) if produced on a commercial scale
The main drawback is that spiders cannot be farmed on a commercial scale
In collaboration with Nexia Biotechnologies, Randy Lewis has developed an alternate
harvesting method: a goat that produces the spiders’ web protein in its milk
To create “spider goat”, researchers inserted a spiders’ dragline silk gene into the goats’
DNA so that the goats would make the silk protein only in their milk
Then, the silk protein would be extracted from the milk of transgenic goats that have the
spider silk gene inserted into their DNA
This “silk milk” could then be used to manufacture a web-like material called Biosteel.
Although spider goats are transgenic animals, the goats behave and look like any other
farm goats (they do not look like a spider and goat hybrid!)
Gene Therapy
-picture Remove or alter viral DNA so that the viruses cannot harm the cells
 Copies of the DNA that include the normal human gene are placed inside each virus and
incrorporated into the virus’s own DNA
 Large numbers of these viruses are used to infect the target cells in an attempt to insert
the normal human DNA into the cells’ genome
Obstacles
 Many treatments may be necessary due to divisions
 Not possible to control where a gene is inserted
 Monitor body immune system
 Virus may recover its ability to cause disease once it is in the target cell
 Many disorders are caused by more than one gene
 The vector must be able to reach all or most of the target cells
Successes
 Inherited blindness
o In dogs
o Childhood blindness
 Duchenne muscular dystrophy
o Possible to repair the gene
 Deafness
o Stimulate new hairs
Questions:
1. Make a list of pros and cons of using recombinant DNA technology in the food industry.
2. Why are engineers interested in being able to produce large amounts of spider silk?
3. What characteristics enable viruses to be used as vectors in gene therapy?
4. What are 3 challenges that scientists have to overcome in gene therapy?
5. Make a list of ethical considerations for using gene therapy.
6. What are 2 reasons genetic engineering is helpful?