Read the passage below. Use the information in the passage and your own knowledge
to answer the questions that follow.
Therapeutic Cloning versus Reproductive Cloning
Some people find the idea of cloning frightening. They have an image of
identical human beings being created by scientists. This is why some people
were concerned when Dolly the sheep was created by reproductive cloning.
Therapeutic cloning is different as it could help to repair damaged tissue, for
5 example in the treatment of diabetes, heart disease or the loss of photoreceptors
in the eye that cause blindness.
The procedure involves putting an adult body cell nucleus into an enucleated
egg cell. This egg cell is then stimulated to divide into an embryo. Some cells
in this embryo are called stem cells. This means they have the ability to develop
10 into many different cell types. The stem cells are removed and can be used to
treat diseases in any body organ or tissue by replacing the damaged cells.
This type of therapy reduces the risk of rejection by the immune system. Cells
from another person would be recognised as being foreign and would be
attacked by the immune system. This rejection of foreign tissue is a major
15 challenge of organ transplants, alongside the fact that there is a huge shortage
of available organs for donation.
Some scientists hope that the stem cells created by therapeutic cloning might be
useful in the treatment of heart disease. Heart disease is a major cause of death
in the UK. It reduces the transport of oxygen to heart muscle cells and eventually
20 kills them. The remaining living cells attempt to keep the heart pumping but
heart failure may occur. Replacing damaged heart muscle tissue using stem
cells, created by therapeutic cloning, may offer people a chance to survive heart
failure. Studies show that stem cells injected directly into damaged heart tissue
improve heart function and help with the formation of new capillaries.
25 Therapeutic cloning does result in the destruction of an embryo after the stem
cells are removed and this destruction has caused concern over the morality of
the procedure. Also, because therapeutic cloning uses a body cell nucleus, there
is still concern that a scientist may attempt to move beyond therapeutic cloning
and create a cloned human being.
In cloning, an adult body cell nucleus is put into an enucleated egg cell.
What is meant by the term enucleated (line 7)?
(1)
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