Genetic engineering: technique and applications
Biology · GCSE · The School
Isolating and inserting a gene
The desired gene is cut from the donor organism's DNA, using a restriction enzyme that cuts DNA at a specific sequence. The same enzyme cuts open a VECTOR — often a bacterial plasmid, a small circular piece of DNA. The gene is inserted into the vector using another enzyme, ligase, which joins the cut ends back together.
Getting the gene into the target organism
The vector, carrying the new gene, is inserted into the target organism's cells. In a plant, this might use a bacterium that naturally transfers DNA into plant cells. In an animal or microorganism, other methods are used instead. Once inside, the organism's own cellular machinery reads the new gene and makes the protein it codes for.
A worked example: insulin production
Human insulin was once extracted from animal pancreases. Supply was limited, and the match to human insulin was imperfect. Now the human insulin gene is inserted into bacteria, grown in large fermenters. The bacteria read the inserted gene and produce genuinely human insulin, in large, reliable quantities. A direct medical use of the same gene-transfer technique.
GM crops: another application
A crop can be modified to resist a herbicide. Then a field can be sprayed to kill weeds without harming the crop itself. Or it can be modified to make its own pesticide, cutting the need to spray one separately. Golden rice has been modified to make beta-carotene, addressing vitamin A deficiency where rice is a dietary staple.
A benefit worth stating precisely
A GM crop can raise yield and cut reliance on separately applied pesticides. GM bacteria can mass-produce a needed protein, like insulin, more reliably than extracting it from animals. Naming the SPECIFIC benefit for the specific example asked about scores higher than a vague claim that "genetic engineering helps people".
A concern worth stating precisely
One concern: a modified gene spreading to wild relatives of a crop through cross-pollination. Another: uncertainty about long-term effects on ecosystems. A third: patented GM seed forcing farmers to buy new seed every year, rather than saving their own. A good answer names a SPECIFIC concern tied to the example given, not just that "some people worry about GM food".