The process of “destroying” an unwanted gene is called gene silencing and can be done via RNA interference (RNAi). RNAi is a way to silence the BLG gene using specially designed RNA molecules that target the BLG gene mRNA and cause it to produce only a very small amount of BLG protein. Gene silencing is accomplished by first producing RNAs complementary to the mRNAs encoding BLG proteins that need to be “knocked down.” These RNAs are introduced into the cow's cells. They bind to microRNAs and Argonaute proteins to form a silencing complex. The silencing complex binds to BLG mRNA by RNA base pairing. This happens because the RNA introduced into the cell has been specially designed to be complementary to the BLG protein mRNA. This ensures that the silencing complex binds only to the mRNA of that protein. When the silencing complex cleaves the mRNA for the BLG protein, the resulting small mRNA fragments cannot be translated into full-length proteins. By splitting mRNAs into fragments that cannot be completely translated into proteins, the BLG gene was “knocked down.” However, RNAi does not completely knock down BLG gene expression. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay. Some translation can still take place and BLG proteins are therefore still produced. This means that the BLG gene will always produce a very small amount of BLG protein, so cow's milk will contain low levels of BLG protein. Milk produced by these cows with the “knocked down” BLG gene will no longer contain high levels of BLG protein. When cow's milk is drunk, it will not cause the same magnitude of allergic reactions in sensitive people because the production of the BLG proteins that cause these reactions has been reduced. There are both advantages and disadvantages to producing a transgenic cow that produces milk containing human myelin sheath protein (a therapeutic protein). The advantages are that the protein can be easily extracted from cows' milk and administered to people with certain human diseases. Human myelin sheath protein can be used to treat these people. This means that these people do not have to live with this disease and can therefore live longer than expected. Another advantage of producing this therapeutic protein in transgenic cows is that a large capacity of protein can be produced. The average dairy cow can produce a large amount of therapeutic protein (approximately 5 to 10 g/L). Transgenesis is also very economical and it is easy to scale up or down production to meet demand. Genetic manipulation in cows is more specific than conventional breeding because a specific trait can be targeted and is faster than conventional breeding which is slow and unpredictable. The downsides are the time it takes to create a transgenic cow. It takes a long time to generate and validate transgenic cows, which could offset the benefits that transgenic cow's milk will have on humans. Additionally, the proteins produced in cow's milk can only be harvested after the cow begins lactation. Another disadvantage is that the human gene inserted into the cow's genome (transgene) can affect the cow by disrupting a gene necessary for an important function. In fact, the transgene is inserted randomly into a chromosome. Enzymatic pathways may be affected and new.