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Sample essay topic, essay writing: The History Of Cloning - 1114 words
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The theory of being able tomake a genetic copy (a clone) of another animalhas been around for quite a while. In this sectionas the title reads I will show the history of cloning.400 million years B. C.- Plants have been cloningthemselves since not to long (as far as the Earth isconcerned) after their introduction to our planet.They send out runners that create an identicalcopy of the parent plant. 1938- Hans Spermann,of Germany, envisions what he calls the 'fantasticalexperiment'. He suggests taking the nucleus from acell in the late-stage embryo and transplanting thatnucleus into an egg. 1952- Scientists RobertBriggs and T.J.
King use a pipette to suck thenucleus from the cell of an advanced frog embryo,they then add it to a frog egg. The egg didn'tdevelop. 1970- John Gurdon tries the sameexperiment with the same procedure. The eggsdeveloped into tadpoles but died after they wereready to begin feeding. He later showed thattransplanted nuclei revert to an embryonic state.1973- Ian Wilmut just finishes his doctorate atCambridge University when he produces the firstcalf born from a frozen embryo
Cows only givebirth to five to ten calves in a lifetime. By takingfrozen embryos produced by cows that providethe best meat or milk then transferring that tosurrogate mother it allows cattle farmers increasethe quality of their herd. Mid to late 1970's-Scientists cut down small forests publishingresearch papers arguing the ethics of cloning and ifit can be done. While they do this other researchesaround the world are actually investigating if it canbe done. 1981- Karl Illmensee and Peter Hoppereport that they clone normal mice and embryocells.
It is later found to be a fraud. 1982- JamesMcGrath and Davor Solter report that they cannot repeat the mouse cloning experiment. Theyconclude that once mouse embryos reach the twocell stage they cannot be used for cloning. Othersconfirm their results. 1993- Embryologists atGeorge Washington University cloned humanembryos: they took cell groups from 17 humanembryos (defective ones that an infertility clinicwas going to discard), all two to eight cells in size.They teased apart cells , grew each one in a labdish and a few got to 32 cells- a size when theycan be planted into a surrogate mother, althoughthey weren't.
1994- Neal First cloned calves thathave grown to 120 cells. 1996- Ian Wilmutrepeated First's experiment with sheep but putembryo cells into a resting state before transferringtheir nuclei to sheep eggs. The eggs developedinto normal embryos then into lambs. 1997- IanWilmut and his colleague Keith Campbell clone anadult sheep. Different Methods: Of Cloning Themost famous sheep in history, Dolly, was clonedby using the method of Nuclear transfer.Previously the only cloning was either done onplants or frogs or mice. In this section the differentprocesses will be described.
PLANT CLONINGGardeners have been cloning plants for centuriesand plants have been doing it for longer. Here arethree different types of cloning out of many. Onetype of plant cloning naturally occurs when a plantgrows a runner. The runner grows horizontallyacross the ground forming a carbon copy of thatsame plant at the end. Eventually the runner diesand the daughter plant is separated from themother plant. Another is when you cut a branch orleaf off of a plant and plant it.
It will grow anotheridentical plant. That method is called a cutting. Astolon is where a weak branch of a plant falls overand the tip touches the ground. The tip swells androots are formed so that growth in the plant cancontinue. ANIMAL CLONING Lower forms ofanimals clone themselves quite often like amoeba'sand paramecium which use binary fission to splitthemselves in half and create a new but identicalanimal. The only other kind of cloning in animals isnuclear transfer cloning.
Which is the whole topicof this report. Nuclear transfer is when the nucleusof one cell is implanted into another cell that hashad the nucleus taken out. The first time thishappened was when Robert Briggs and T.J. Kingtook the nucleus out of a multi-cell embryo andimplanted it into the egg. Cell division then takesplace 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 anadult animal is cloned.
What happened in Dolly'scase is that Ian Willmut and his team of scientiststook a nucleus from a Finn Dorset sheep andsubstituted it with a nucleus of an egg from a PollDorset. Once the egg had developed to embryostage it was implanted into a third breed of sheepa Scottish Blackface. Dolly came out 148 dayslater as an exact genetic copy of the Finn Dorset.The other important thing about Dolly is that hergenes came from a dead sheep. The cells camefrom a frozen mammary gland. This is explainedbetter by the magazine 'New Scientist.' Themouse is embryonic, the sheep is the cloning ofadult animals.
Earlier cloning could duplicateembryos. Mouse A Mouse B Male and femalemated Mouse X An undeveloped embryo,characteristics unknown. Mouse Y Nucleus of cellfrom X inserted into one of Mouse Y's egg cells,which starts dividing. Mouse Z Healthy mouseGenetically identical to X. New Method duplicatesan adult Sheep X An adult cells were taken fromher udder.
Nucleus of cell from X inserted intoSheep Y's egg cell electric shock makes it startdividing. Sheep Z Carried embryo in her uterus (acommon surrogate breeding technique) Clone ofSheep X Healthy sheep genetically identical to XThe Cloning Debate The thought of cloning tosome people is repulsive and immoral. Othersthink that it is a scientific breakthrough to bevalued for its own worth. Anti-cloners believeMan should not meddle in God's business ofcreating new beings. They take from the Bible thisquote which supports their beliefs: 'For I testifyunto every man that heareth the words of theprophecy of this book, if any man shall add untothese things, God shall add unto him the plaguesthat are written in this book: And if any man shalltake away from the words of the book of thisprophecy, God shall take away his part out of thebook of life, and out of the holy city, and from thethings which are written in this book' [Revelations22:18-19]. Advocates for cloning respond bystating that when the airplane was invented peoplehated the idea and said that if God wanted men tofly he would of given them wings.
Now airplanesare thought of as one of the safest and fastestways of travel. Human cloning presents manyethical problems because it is playing with Lifeitself. The father of cloning Ian Wilmut statedbefore the U.S. subcommittee on health lastMarch. ' In previous work with cells fromembryos, three out of five died soon after birthand showed developmental abnormalities. Similarexperiments with humans would be totallyunacceptable.' While that argument is good,almost no experiment can be done perfectly thefirst time.
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