ÜDS-Fen 2001-2 Soru=63

As the passage points out, genetic change is not a new phenomenon, but .

Scientists can now speed up the process of genetic
change through biotechnology. Farmers need no longer
wait patiently for breeding to yield improved crops and
animals, nor must they even respect natural lines of
reproduction among species. Laboratory scientists can
now select desirable traits from any of a number of
species and insert those traits into the genetic material of
crops and animals. Among the new products of
biotechnology are tomatoes that stay fresh much longer
than the usual ones and so promise less waste and
higher profits. Normally, tomatoes produce a protein that
softens them after they have been picked. Scientists
introduce into a tomato plant a gene that is a mirror
image of the one that codes for the "softening" enzyme.
This gene fastens itself to the RNA of the native gene
and blocks its action. A vine-ripe tomato with this special
gene rots more slowly than a normal tomato, allowing
growers to harvest at the most flavourful and nutritious
red stage. The tomatoes will still last much longer during
shipping and marketing than regular tomatoes harvested
when green.