Pros and Cons of Transgenesis

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Zoë Zegers


Richetelli 3/4

Transgenic Organisms

Transgenic organism is an organism that has been engineered to carry genes from another species. In this way organism can be made to produce different protein than it normally would. The reason why Transgenesis is possible is because DNA in all organisms is the same if a scientist removes a segment of DNA from one organism and injects it into another then the cell of the second organism will read and use the new DNA as if it was its own. Transgenic organisms, as well as all genetically modified organisms (GMO), are highly debatable because although uses are infinite there are environmental and ethical issues that question the use of GMOs.

In 1973, a little less than 100 years after Mendel first formulated the laws of hereditary, Herbert Boyer created the first transgenic organism. He combined one bacterium with a virus and then injected that virus into an E. coli bacterium. This method is similar to the retrovirus-mediated gene transfer. Boyer then went on to create the Genentech in 1976. A year later Genentech used this technology to create a bacteria that produced insulin. In 1974 the first transgenic animal, a mouse, was created. Since then many companies have been using transgenesis to create unique products with desirable qualities.

There are three different methods to go about transgenesis DNA microinjection, retrovirus-mediated gene transfer, and embryonic stem cell-mediated gene transfer. The most of common of the 3 for the creation of transgenic animals is microinjection. The advantage of microinjection is that it is applicable to many different species. However, the disadvantage is a low success rate “only 0.6% of transgenic pigs were born with a desired gene after 7,000 eggs were injected with a specific transgene” (Endang Tri Margawati).  The process of microinjection involves a direction injection of a gene from one organism into the pronucleus of a zygote. The new cell develops in vitro in a lab until it is at a specific embryonic phase and then transfers it into a surrogate female. The next method of transgenesis is retrovirus-mediated gene transfer. A retrovirus is a virus that has RNA instead of DNA. Retroviruses are used to inject their genetic material as well as the transgene into the host cell.  The result of this is a chimera, an organism that consists of tissues or parts from different types of organisms. These chimeras are inbred for as many as 20 generations until the transgenic offspring are homozygous. The last method, embryonic stem cell-mediated gene transfer begins with the isolation of totipotent stem cells, stem cells that can become any kind of specialized cell, from embryos. Then the transgene is put into the isolated cells. The cells with the transgene are integrated into the host embryo. The method, unlike the other two, does not need a living transgenic offspring to determine whether or not the transgene is present. The most important thing about a successful transgenic organism is that it is able to pass along the transgene to their offspring.

There are many benefits that have come into existence due to transgenic organisms. These benefits can be grouped into 3 categories, agriculture, medical and industrial. New breakthroughs are constantly being made because the unlimited combinations of genes that can allow humans to produce a large variety of necessary products.

Agriculturally there are many different uses that come from transgenic organisms, including making breeding and growing crops easier and more effective, improving the quality of organic products and making crops and animals more pest resistant. Transgenic animals can be manipulated to have greater yields. For example cows with more meat that produce more milk. This would deter farmer from using harmful steroids and growth hormones on their animals. Also crops can produce more of their useful parts, such as the...
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