|MadSci Network: Genetics|
Greetings Xu. Sorry it has taken me so long to reply to your question. The terms transgenic and cloned have quite different meanings. Transgenic is a word usually used to describe an animal (or plant, or perhaps another organism) that has had one or more genes from another cell or organism stably incorporated into its own genome, and is capable of passing on these "foreign" genes on to daughter cells. Therefore a transgenic mouse for example, may have a foreign gene construct stably incorporated into its own DNA, causing the expression of that foreign gene in cells and tissues that it may not otherwise be expressed in. Further, the expression level of the foreign gene in the transgenic organism is generally different from the levels in which the original gene is expressed in the host cell/organism. Creating transgenic mice that overexpress (or underexpress) a given gene can be very useful for studying its function. Another term, knockout, is used to describe organisms that have a given gene inactivated (no gene expression). These are also very useful for studying the function of a given gene. A cloned animal on the other hand is an organism that is genetically identical to the original organism from which it was derived. A famous example of the latter is Dolly, the lamb cloned from an adult sheep udder cell. Interestingly, as I was writing this reply I was informed by a colleague that an Italian fertility specialist has just claimed that one of his patients is pregnant with the worlds first cloned baby. I am not sure how true this claim is, but the following link is to a news report I found on the issue - http://www.cnn.com/2002/TECH/science/04/06/human.clone/index.html. I hope this is helpful. Cheers. Luke.
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