outline the processes used to produce transgenic species and include examples of this process and reasons for its use
Transgenic organisms contain a gene (transgene) from another species. This is acheived through recombinant DNA technology. Recombinant DNA technology manipulates DNA by the use of restriction enzymes, ligases and PCR (polymerase chain reaction). Restriction enzymes are used to cut DNA in specific places. These enzymes are also known as gene scissors or gene shears. Different restriction enzymes cut DNA in specific parts. The cut ends are known as ‘sticky ends’. Ligases are used to repair and strengthen DNA especially after it has been cut by restriction enzymes. PCR is used to produce many copies of the recombinant DNA formed by the previous processes.
Once the recombinant DNA is produced there are processes used to insert the DNA into the host species. These processes include microinjection, Ti plasmid insertion, gene gun and electroporation.
In microinjection a fine glass needle is used to insert the recombinant DNA into the nucleus of the host cell.
Ti (tumour inducing) plasmid insertion uses a bacterium called Agrobacterium tumefaciens. These bacteria produce crown gall in plants by inserting some of their own DNA into the host DNA causing the plant to produce a gall in which the bacteria live. The ability of the bacteria to insert DNA is used to transfer DNA into the host species.
The gene gun blasts small metal pieces coated with DNA into the nucleus of the host cell.
Electroporation uses electric pulses to create small pores in the nuclear membrane through which DNA is inserted.
Examples of transgenic species are genetically engineered salmon which have the gene coding for the protein, bGH (bovine growth hormone), and potato plants which have a pea gene for lectin inserted.