Cloning

This essay has a total of 2484 words and 11 pages.

Cloning


The History of Cloning
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 whole topic of this report.
Nuclear transfer is when the nucleus of one cell is implanted into another cell that has had the nucleus taken out. The first time this happened was when Robert Briggs and T.J. King took the nucleus out of a multi-cell embryo and implanted it into the egg. Cell division then takes place and forms into a tadpole then into a frog. This process has been repeated with mice, sheep, monkey's, etc. That is called embryonic cloning. The kind of cloning that created Dolly is when an adult animal is cloned. What happened in Dolly's case is that Ian Willmut and his team of scientists took a nucleus from a Finn Dorset sheep and substituted it with a nucleus of an egg from a Poll Dorset. Once the egg had developed to embryo stage it was implanted into a third breed of sheep a Scottish Blackface. Dolly came out 148 days later as an exact genetic copy of the Finn Dorset. The other important thing about Dolly is that her genes came from a dead sheep. The cells came from a frozen mammary gland.

This is explained better by the magazine "New Scientist." The mouse is embryonic, the sheep is the cloning of adult animals. Earlier cloning could duplicate embryos.
Mouse A
Mouse B
Male and female mated
Mouse X
An undeveloped embryo, characteristics unknown.
Mouse Y
Nucleus of cell from X inserted into one of Mouse Y's egg cells, which starts dividing.
Mouse Z
Healthy mouse Genetically identical to X.
New Method duplicates an adult
Sheep X
An adult cells were taken from her udder.
Nucleus of cell from X inserted into Sheep Y's egg cell electric shock makes it start dividing.
Sheep Z
Carried embryo in her uterus (a common surrogate breeding technique)
Clone of Sheep X
Healthy sheep genetically identical to X

The Cloning Debate
The thought of cloning to some people is repulsive and immoral. Others think that it is a scientific breakthrough to be valued for its own worth.

Anti-cloners believe Man should not meddle in God's business of creating new beings. They take from the Bible this quote which supports their beliefs: "For I testify unto every man that heareth the words of the prophecy of this book, if any man shall add unto these things, God shall add unto him the plagues that are written in this book: And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book" [Revelations 22:1819].

Advocates for cloning respond by stating that when the airplane was invented people hated the idea and said that if God wanted men to fly he would of given them wings. Now airplanes are thought of as one of the safest and fastest ways of travel.

Human cloning presents many ethical problems because it is playing with Life itself. The father of cloning Ian Wilmut stated before the U.S. subcommittee on health last March. " In previous work with cells from embryos, three out of five died soon after birth and showed developmental abnormalities. Similar experiments with humans would be totally unacceptable." While that argument is good, almost no experime

Read essay without registering

Donate an essay now and get the full essay emailed you




Acceptable files: .txt, .doc, .docx, .rtf

Email Address