Genetic
engineering
Since
traits come from the genes in a cell, putting a new piece of DNA into a cell can
produce a new trait. This is how genetic engineering works. For example, crop
plants can be given a gene from an Arctic fish, so they produce an antifreeze
protein in their leaves. This can help prevent frost damage. Other genes that
can be put into crops include a natural insecticide from the bacteria Bacillus
thuringiensis. The insecticide kills insects that eat the plants, but is
harmless to people. In these plants the new genes are put into the plant before
it is grown, so the genes will be in every part of the plant, including its
seeds. The plant's offspring will then inherit the new genes, something which
has led to concern about the spread of new traits into wild plants.
The
kind of technology used in genetic engineering is also being developed to treat
people with genetic disorders in an experimental medical technique called gene
therapy. However, here the new gene is put in after the person has grown up and
become ill, so any new gene will not be inherited by their children. Gene
therapy works by trying to replace the allele that causes the disease with an
allele that will work properly.