Genetic Engineering

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Genetic Engineering

I . Introduction

One way of identifying cells carrying a particular gene is by assaying for the gene product . Such products are themselves , of course , a frequent objective of genetic engineering . Most of the earliest work in genetic engineering made use of E . coli to synthesize the gene product E . coli has the advantage that researchers are very familiar with this easily grown organism and with its genetics . It also has several disadvantages . Like other gram-negative bacteria , it produces endotoxins as part

of its outer layer . Since endotoxins cause fever and shock in animals , their accidental presence in products intended for use in humans would be a serious problem . Another disadvantage of E . coli is that it does not usually secrete protein products (Old Primrose 21-27 . To obtain a product , cells must usually be broken open and the product purified from the resulting soup ' of cell components

Recovering the product from such a mixture is expensive when done on an industrial scale . It is more economical to have an organism secrete the product so that it can be recovered continuously from the growth of natural E . coli protein that the bacterium does secrete . This approach has been used to produce insulin . Certain gram-positive bacteria , such as Bacillus subtilis , are more likely to secrete their products and are often industrially for that reason

Another microbe that shows promise as a vehicle for the expression of genetically engineered genes is baker 's yeast , Saccharomyces cerevisiae Its genome is only about four times larger than that of E . coli and is probably the best understood eukaryotic genome . Yeasts may carry plasmids , and their cell walls can readily be removed to introduce plasmids carrying engineered genes . As eukaryotic cells , yeasts may be more successful in expressing foreign eukaryotic genes than bacteria Furthermore , yeasts are likely to continuously secrete the product Because of all these factors , yeasts have become the workhorse of eukaryotic cells . Yeasts also have a psychological advantage in the marketplace (Chilton , 50-59 . Bacteria and viruses are , unfairly associated in the public 's mind with diseases , whereas yeasts have a much more benign image , thanks to their association with baking brewing , and wine-making

Thesis Statement : This study gives deeper understanding of genetic engineering and its used

II . Background

Animal viruses have also been used in making engineered gene products primarily in the field of vaccine production . For example , scientists have been able to insert genes for the surface proteins of pathogenic microbes into the generally harmless vaccinia virus . The result is a sort of sheep in wolf 's clothing ' a virus that has the external proteins of a pathogen but does not cause disease . When an animal host is infected with the engineered virus , the host 's immune system recognizes these proteins as foreign and , in response , develops an immunity that can protect it against the cultural pathogen . Because the vaccinia virus is unusually large and has room for several extra genes a genetically engineered vaccinia virus...