Genetic Engineering Methods
There are generally three methods that are used to introduce a foreign gene into a plant or animal: Plasmid, Vector, and Biolistic.
The plasmid method is often used to alter the genome
of a bacteria. It is performed by first treating
both the bacteria and the desired gene with
the same restriction enzyme. By doing so it
creates "sticky ends" on both the bacterial
DNA and the gene's DNA. Given the opportunity
these sticky ends will join with each other.
Scientist's select the bacteria that have absorbed
the new gene and can the use this bacteria to
implement the gene into plants or animals.
The vector method is performed using viral vectors that will transmit the DNA to the host. It begins in a very similar fashion to that of the plasmid method, but is more reliable to use to implement the desired traits into the host cells. After the trait from the viral vector is inside the host cell, the cell will then go on to replicate the trait itself with its own genetic information.
The Biolistic method is also know as the bioballistic method, and utilizes very small slivers of metal coated with the desired trait to insert themselves in the genetic material of the host cell. This is accomplished by coating metal - usually tungsten - and firing these coated slivers from a shotgun like apparatus at the cells. The cells that take up the desired gene are then cultured to replicate the gene. This is the most useful method for inserting genes into plant cells.
The first most likely approach for directly
manipulating human genes is germline
gene therapy. Rather than just screening
embryos for disorders as with the current PGD
process, germline therapy would actually introduce
new genes into the cells. Any traits deemed
desireable can be made "indigenous" to the embryo
as if they were inherited naturally.
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