A clone is a group of organisms that are genetically identical. Most clones
result from asexual reproduction, a process in which a new organism develops
from only one parent. The one process of cloning, called nuclear transfer,
replaces the nucleus of an immature egg with a nucleus from another cell. Most
of the work with clones is done from cultures. An embryo has about thirty or
forty usable cells but a culture features an almost endless supply. When the
nucleus has been inserted into the egg cell, the cell is given an electric shock
to initiate the development. Traditionally this is the sperm?s role. In this
paper we will be discussing the advantages of different types of clones, such as
they are useful for research. We will also be discussing the disadvantages and
different techniques that result from the cloning of different organisms.
First lets start with the history of cloning. The modern era of
laboratory cloning began in 1958 when F.C. Steward cloned carrot plants from
mature single cells placed in a nutrient culture containing hormones. The first
cloning of animal cells took place in 1964. John B. Gurdon took the nuclei from
tadpoles and injected them into unfertilized eggs. The nuclei containing the
original parents? genetic information had been destroyed with ultraviolet light.
When the eggs were incubated, Gurdon discovered that only 1% to 2% of the eggs
had developed into fertile adult toads. The first successful cloning of mammal
was achieved nearly twenty years later. Scientists from Switzerland and the U.S.
successfully cloned mice using a method similar to Gurdon?s, but required one
extra step. After the nucleus was taken from the embryos of one type of mouse,
they were transferred into the embryos of another mouse who served as the
surrogate mother. This mouse went through the birthing process to create the
cloned mice. The cloning of cattle was achieved in 1988, when embryos from prize
cows were transplanted to unfertilized cow eggs whose own nuclei had been
removed. In 1993 the first human embryos were cloned using a technique that
placed individual embryonic cells (blastomeres) in a nutrient culture where the
cells then divided into 48 new embryos. These fertilized eggs did not develop to
a stage that could be used for transplantation into a human uterus.
Cloning can do many good things for our wild life and for our economy.
The process of cloning can save us a lot of money. A crop that is imported to
our country can instead be cloned here. It would also make the product cheaper.
Cloning would also develop stronger plants, resistant to disease, parasites, and
insect damage. With...