Timeline

1902: Walter Sutton proves chromosomes contain genetic information

1902: Hans Spemann divided a salamander embryo into halves and showed early embryo cells contains all the genetic information necessary to create a new organism.

1907: Thomas Hunt Morgan begins work on first ‘chromosome map’. The American scientist made the map to show the location of genes. He used fruit flies in his tests.

1928: First Nuclear transfer experiment conducted by Hans Spemann

1938: Cloning with differentiated cells by nuclear transfer first envisioned by Hans Spemann.He proposed this that experiments on cloning organisms by extracting the nucleus of a differentiated cell and inserting it into an enucleated fertilized egg, which he called the ‘fantastical experiment'.

1944: American Oswald Avery located the nucleic acid DNA as the carrier of genetic information, instead of proteins in the cell.

1950: Alfred Hershey and Martha Chase use radioactively labelled E. coli to prove that DNA and not proteins had penetrated interior of cells and was the true carrier of heredity.

1952: Briggs and King cloned tadpoles

1953: Shape and structure of DNA discovered by American James Watson and English Francis Crick.

1958: F.S. Steward (U.S.) grew complete carrot plants from differentiated carrot root cells, showing that cloning from differentiated cells is in fact biologically possible.

1962: John Gurdon claimed to have cloned frogs from adult cells

1964-6: Marshall Nirenburg, Heinrich Mathaei, and Severo Ochoa cracked the genetic code.

1973: Two U.S. researchers, Herbert Boyer and Stanley Cohen, conducted the first successful experiment on recombinant DNA.

Boyer and Cohen created the first recombinant DNA organism using recombinant DNA technology, or gene splicing, which allows the manipulation of DNA. They removed plasmids, small rings of DNA located in a cell’s cytoplasm, from a cell. They cut the DNA at precise positions and then recombined the DNA strands in their own way using DNA ligase enzyme. They then inserted the altered DNA.

1977: Karl Illmensee claims to have cloned mice with only one parent

1979: Karl Illmensee claims to have cloned 3 mice

1983: The polymerase chain reaction (PCR) technique for rapid DNA synthesis devised by Kary B. Mullis.

1984: Steen Willadsen cloned a sheep from embryo cells – the first mammal proved to be cloned using nuclear transfer.

1986: Willadsen cloned a cow from differentiated, 1 week old embryo cells, showing that genetic information of a cell did not decrease as a cell specialize.

1990: New DNA was created to inject into people to do the work of defective genes so as to boost the body’s defense.

1994: Dr. Ned First (U.S.) clones calves from cells of early embryos

1993: First humans cloned (U.S.). Cells taken from defective human embryos were developed up to 32-cell stage, then destroyed.

1995: Dr. Ian Wilmut and Keith Campbell (U.K.) create the world's first cloned sheep, Megan and Morag, from differentiated embryo cells.

1996: July – Dolly, the first cloned sheep, was cloned by nuclear transfer from adult cells

1997: July – Wilmut’s team created Polly, the first genetically engineered sheep with human genes.

1998: Yanagimachi’s team created 22 mouse clones with nuclear transfer, and also clones of clones.

1998: Experiments with cell-repair genes show that it may be possible to extend human lifespan by 40%. Researchers said that old people can still be active and mostly free of diseases.

1998: An endangered breed of New Zealand cattle was cloned by nuclear transfer, opening the door to cloning to save endangered species.

1999: Calves were cloned from frozen cells taken from a Japanese beef bull. The experiment, led by Dr. Xiangzhong Yang, proved that cells can be stored for later cloning.

1999: September – Tetra, the first cloned monkey, cloned by embryo splitting.

1999: December - Dolly may show premature aging

2000: May – Cloned cow shows that cloning can rejuvenate cells

Pros and Cons Of Cloning

PROS

1) The possibility of producing not a complete body but just an organ to save the life of human being, who might need a organ transplant.
2) Cloning can also allows the production of animals facing extinction and maintain ecological balance.
3)Cloning can help us to understand why some of our cell, don't multiply.
4)The quality of clone is know perfect well its characteristics are identical 99% with the original DNA.
5)Cloning will allow us to understand why certain cell suffer an unnecessary reproduction.
6)The freedom to produce.
7)Cloning might also enable a sterile woman to have a child from her own body, using any cell from he organism.
8)Cloning may make it possible to reproduce a certain trait in human beings. Cloning can be able to produce people with certain qualities, human beings with particular desirable traits and making human being man made.
9)Cloning will help us to understand the composition of genes and the effects of genetic constituents on human traits, in a better manner.
10)Cloning will help us to over come a wide range of genetic diseases.

CONS

1)When cloning an identical organism or gene, it lessens the ability of adaption in the organism or gene and the organism or gene can easily get disease.
2)Although cloned animals and human will be identical, it will only live half of the life span of the normal animal or human, which has benn cloned.Dolly the sheep is an example of identical cloning, but the Dolly only lived 6 years, where sheep's life span is 10 years.
3)cloning is inbreeding, as everyone has the same DNA and keep reproducing among themselves. This would lead us to our own extinction.
4)Risk of having a same disease, if we all are clone and then we could die.

Cloning In Organisms

Organism cloning (also called reproductive cloning) is a procedure of creating a new multi cellular or genetically identical to anther. This type of cloning is an asexual method of reproduction, where fertilization does not take place.
Dolly is am example of reproductive cloning. Dolly was created by reproductive cloning technology, in a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from a nucleus of a donor adult cell to an egg whose nucleus, and thus it genetic material has been removed. The reconstructed egg containing the DNA from an adult must be treated with chemicals in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host, where it continues to develop until birth.

Ethical/Social Issues of Cloning

While the research and the success in genetic research and testing has brought up a lot of exciting possibilities as well as great advances and discoveries, it has also raised many ethical issues: Should research institutes profit from our DNA? Should patients be tested for untreatable conditions? How private is a person's genetic information? These issues involve researchers, lawyers, religious groups and even random people who walk the streets.

"Cloning looks like a degrading of parenthood and a perversion of the right relation between parents and children"
Leon Kass

Sucessful Cloning So Far

So far scientists have been able to clone salamanders, mice, flies and other living animals. The first cloned mammal was Dolly the Sheep. The cloning od Dolly came after many failures. The scientific team that produced the Dolly, first cloned sheep, reported that it took 277 eggs to produce 29 sheep embryos; of these only three survived until birth, and only one of these three - Dolly - lived for any length of time after birth. The cloning of Dolly the Sheep proved that genetic material from an adult cell could be used to grow an identical copy, or clone, of the entire organism.

History of Cloning

The first cloned animals were created by Hans Dreisch in the late 1800's. His main goal was to prove that genetic material is not lost during cell division.

In 1902, embryologist Hans Spemman, separated a 2-celled embryo of a salamander. He later separated a single cell from a 16-celled embryo. In these experiments, both the large and the small embryos developed into identical adult salamanders. He then stated that no genetic material was lost as cells grew and divided.

After a long wait for new cloning discoveries on November of 1951, a team of scientists in Philadelphia cloned a frog embryo. They took the nucleus out of a frog embryo cell and used it to replace the nucleus of an unfertilized frog egg cell. Once the egg cell noticed that it had a full set of chromosomes, it began to grow. This process is called nuclear transplant and it was made that day. We still continue to use this method but made few changes to it.

Cloning in Nature

Cloning has been going on in the natural world for thousands of years. A clone is just one living thing made from another, leading to two organisms with the same set of genes.
Plants that are self pollinated will produce seeds that will eventually grow into more plants with the same DNA or genetic code. Some forests are made entirely of trees spawning from one single plant. This happens because the original tree spread its roots, which later sprouted new trees. Although there are many cons of this sort of cloning because, if the species of trees get infected they all do.
An excellent example of cloning in nature is when an earthworm is cut in half, it'll be able to grow back the missing parts of their bodies, leading to two worms with the same set of genes. Lastly, not many people realize it but giving birth to twins is also categorized as cloning since they are born sharing their DNA.