Read the passage below. Use the information in the passage and your own knowledge
to answer the questions that follow.
Transgenic animals
The term ‘transgenic’ means the transfer of genetic material from one species to
a different species. Cattle, pigs or sheep are made to superovulate and their eggs
are collected. The eggs are fertilised and a desired gene is injected into them
using a needle. Some of the fertilised eggs take up the gene, which becomes part
5 of one of the animal’s chromosomes. The fertilised eggs develop into embryos
which are cultured and then implanted into surrogate mothers to complete their
development.
In 1993, the world’s first transgenic lamb, known as Tracy, was produced from a
fertilised egg which had been injected with a human gene. When Tracy became
10 an adult sheep she was able to produce milk containing the human protein AAT.
This protein can be used to treat human lung diseases such as emphysema and
cystic fibrosis.
Tracy looked like a normal sheep and was able to reproduce. She gave birth to
two lambs, one of which inherited her ability to produce AAT milk. Tracy showed
15 that human proteins could be made in other mammals and extracted from
their milk. This technique can now be used to obtain milk that contains specific
antibodies or blood clotting factors.
Another potential use of transgenic animals is to produce organs for transplanting
into humans. This is important because of the decreasing availability of human
20 organ donors and the increasing demand for organs.
Transgenic technology can also be used to transfer genes into cattle for disease
resistance, increased meat production and increased ability to digest cellulose.
Explain what is meant by the term gene (line 3).
(2)
....................................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................................................................