The most common method of genetic engineering is the addition of foreign DNA in the form of recombinant DNA.
Genetically modified organisms have been used for academic, medical, agricultural, and industrial purposes.
The applications will be looked at in more detail in the next module.
There is a short video explaining how scientists create a transgenic animal.
This method is similar to damaging a body part to determine its function.
The wing's function is flight if an insect loses a wing.
The classic genetic method compares insects that can't fly with insects that can.
Deletion or modification of genes gives researchers clues about the function of the genes.
Reverse genetics can be used to cause a gene to over express itself.
It is easy to see how it can be used for medicine.
Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix Mutant genes provides methods to treat diseases.
Crop yield and quality can be improved by enhancing resistance to disease, pests, and environmental stress.
Genetic diagnosis by genetic testing is the process of testing for suspected genetic defects.
If a genetic disease is present in an individual's family, they may be advised to have genetic testing.
A woman with breast cancer can be screened.
If one of the high-risk genes is found, her female relatives may want to be screened for it or be more vigilant for the occurrence of cancer.
Fetal testing can be done to determine the presence or absence of disease-causing genes in families with specific diseases.
You can see how human DNA is used for genetic testing.
In its simplest form, it involves the introduction of a non-mutated gene at a random location in the genome to cure a disease.
The non-mutated gene can be introduced into a cell as part of a virus that can deliver foreign DNA into the cell's genome.
The majority of gene therapies have been done in humans.
Some of the experimental treatments have been successful, but the methods may be important in the future as the factors limiting its success are resolved.
The steps involved in curing a disease are shown in this diagram.
The immune system is stimulated by weakened or inactive forms of viruses.
The immune system is stimulated by large quantities of specific substances that are mass-produced inbacteria.
The substance is used as a vaccine.
The H1N1 flu vaccine uses genes cloned from the virus to combat the constantly changing strains of the virus.
penicillin is the most well known example of an antibiotic being produced by a microorganisms.
Antibiotics can be produced on a large scale.
The antibiotics have been genetically modified to improve their yields.
It used to be only possible to treat diabetes with piginsulin, which caused allergic reactions in many humans.
A eukaryotic animal host is necessary for proper processing of some recombinant proteins used in medicine.
Animals such as sheep, goats, chickens, and mice have genes cloned and expressed in them.
Transgenic animals are animals that have been modified.
Two of the mice have genes that cause them to fluoresce under a UV light.
The non-transgenic mouse does not have the same genes as the transgenic mouse.
The milk of sheep and goats has several human genes in it.
The FDA has approved a blood anticoagulant that is produced in the milk of transgenic goats for use in humans.
Mice have been used for expressing and studying genes.
Genetically modified organisms have helped to create desirable traits such as disease resistance, herbicide, and pest resistance, better nutrition, and better shelf life.
Plants are the main source of food.
Farmers have been selecting plant varieties with desirable traits for a long time.
Corn is a major agricultural crop used to create products for a variety of industries.
Because they contain unique combinations of genes and are not restricted to the laboratory, transgenic plants and other GMOs are closely monitored by government agencies to ensure that they are fit for human consumption and do not endanger other plant and animal life.
Because foreign genes can spread to other species in the environment, extensive testing is required to ensure ecological stability.
The first crops to be genetically engineered were corn, potatoes, and tomatoes.
The thick plant cell wall makes it more difficult to introduce DNA into plant cells.
The plasmids are manipulated to carry the desired fragment into the plant genome.
Within a few hours, insects that have eaten Bt toxin stop feeding on plants.
Within a couple of days, death occurs after the toxin is activated.
Plants are able to produce their own crystal Bt toxin because of the cloned crystal toxin genes.
Bt toxin is safe for the environment and mammals.
It has been approved for use by organic farmers.
There is concern that insects may evolve resistance to the Bt toxin in the same way thatbacteria evolve resistance to antibiotics.
The first GM crop to be introduced into the market was a tomato.
Increased shelf life of GM tomatoes can be attributed to the use of genetic technology to slow down the process of rotting.
The tomato's flavor was improved by additional genetic modification.
The tomato did not stay in the market because of shipping problems.
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