The History of Cloning

Topics: Cloning, Cell, Embryo Pages: 9 (2513 words) Published: January 24, 2000
The theory of being able to
make a genetic copy (a clone) of another animal
has been around for quite a while. In this section
as the title reads I will show the history of cloning.
400 million years B. C.- Plants have been cloning
themselves since not to long (as far as the Earth is
concerned) after their introduction to our planet.
They send out runners that create an identical
copy of the parent plant. 1938- Hans Spermann,
of Germany, envisions what he calls the "fantastical
experiment". He suggests taking the nucleus from a
cell in the late-stage embryo and transplanting that
nucleus into an egg. 1952- Scientists Robert
Briggs and T.J. King use a pipette to suck the
nucleus from the cell of an advanced frog embryo,
they then add it to a frog egg. The egg didn't
develop. 1970- John Gurdon tries the same
experiment with the same procedure. The eggs
developed into tadpoles but died after they were
ready to begin feeding. He later showed that
transplanted nuclei revert to an embryonic state.
1973- Ian Wilmut just finishes his doctorate at
Cambridge University when he produces the first
calf born from a frozen embryo. Cows only give
birth to five to ten calves in a lifetime. By taking
frozen embryos produced by cows that provide
the best meat or milk then transferring that to
surrogate mother it allows cattle farmers increase
the quality of their herd. Mid to late 1970's-
Scientists cut down small forests publishing
research papers arguing the ethics of cloning and if
it can be done. While they do this other researches
around the world are actually investigating if it can
be done. 1981- Karl Illmensee and Peter Hoppe
report that they clone normal mice and embryo
cells. It is later found to be a fraud. 1982- James
McGrath and Davor Solter report that they can
not repeat the mouse cloning experiment. They
conclude that once mouse embryos reach the two
cell stage they cannot be used for cloning. Others
confirm their results. 1993- Embryologists at
George Washington University cloned human
embryos: they took cell groups from 17 human
embryos (defective ones that an infertility clinic
was going to discard), all two to eight cells in size.
They teased apart cells , grew each one in a lab
dish and a few got to 32 cells- a size when they
can be planted into a surrogate mother, although
they weren't. 1994- Neal First cloned calves that
have grown to 120 cells. 1996- Ian Wilmut
repeated First's experiment with sheep but put
embryo cells into a resting state before transferring
their nuclei to sheep eggs. The eggs developed
into normal embryos then into lambs. 1997- Ian
Wilmut and his colleague Keith Campbell clone an
adult sheep. Different Methods: Of Cloning The
most famous sheep in history, Dolly, was cloned
by using the method of Nuclear transfer.
Previously the only cloning was either done on
plants or frogs or mice. In this section the different
processes will be described. PLANT CLONING
Gardeners have been cloning plants for centuries
and plants have been doing it for longer. Here are
three different types of cloning out of many. One
type of plant cloning naturally occurs when a plant
grows a runner. The runner grows horizontally
across the ground forming a carbon copy of that
same plant at the end. Eventually the runner dies
and the daughter plant is separated from the
mother plant. Another is when you cut a branch or
leaf off of a plant and plant it. It will grow another
identical plant. That method is called a cutting. A
stolon is where a weak branch of a plant falls over
and the tip touches the ground. The tip swells and
roots are formed so that growth in the plant can
continue. ANIMAL CLONING Lower forms of
animals clone themselves quite often like amoeba's
and paramecium which use binary fission to split
themselves in half and create a new but identical
animal. The only other kind of cloning in animals is
nuclear transfer cloning. Which is the...
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