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A transgenic animal is one whose genome has been experimentally altered by the stable introduction of a foreign (exogenous) piece of DNA called a transgene. There are many methods used to produce a transgenic animal; however, the method demonstrated in this animation has proven to be very successful.

First, the transgene of interest, along with specific promoter elements necessary for its expression, is injected into one of a fertilized egg's two pronuclei. These haploid pronuclei, one of which came from the egg and one that originated from the sperm, eventually fuse to form a single diploid transgenic embryo nucleus. The transgenic cell produced in this manner ultimately gives rise to the complete animal. In other words, insertion of the transgene at this stage allows for it to be incorporated into all of the cells of the body, including both germ cells and somatic cells. Thus, the transgene can be passed on to future generations. Finally, the transgenic embryo is implanted into a female, and the first generation of transgenic individuals is born.

These animals can be used for many different purposes, including determining the function of individual genes, producing proteins of commercial value, and improving the health and productivity of domestic animals and plants. Scientists can insert genes that have uncertain functions into an animal. From observing the offspring of this animal, the function of the gene and its effects on phenotype and development can be determined.

Trangenic animals can also be used to produce proteins that are needed for people or animals that lack the ability to produce them. An example would be the production of insulin. Some individuals who suffer from diabetes lack the ability to produce insulin in the amounts needed for daily function. Therefore, they need to get insulin from another source. Using the technology of transgenics, scientists have solved this problem by creating animals that possess the gene that makes insulin. The insulin can then be collected from the animals and processed so that it can be sold to those who need it.

Lastly, transgenics can be used to produce better animals and plants that are necessary for the food industry. Cows can be created that have the genes to make milk with added vitamins and proteins. The genes that cold water fish possess to keep them from freezing can be inserted into plants, so they will be able to withstand any mid-harvest freezes that could lead to a loss of important fruits and vegetables. The amount of knowledge that can be gained and positive outcomes that can be achieved by the technology of transgenics is far-reaching.





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