cloning - What is cloning, What is human cloning, Recombinant DNA Technology or DNA Cloning, Reproductive Cloning, Therapeutic Cloning referat

Cloning is a very controversial theme. It is considered by many people and nations as an immoral practice, a bad appendix of science. Cloning does violate the laws of nature, because we are the ones that manipulate it. It interferes with the natural and common reproduction. But we have to consider another point of view. What will happen to the people who can't procreate by the traditional way, nature's way? Don't they have the same rights with us to become happy, to fulfill their wishes of becoming a father or a mother? How can we stop people from practicing the universal right of searching for happiness? If we do it, we would be selfish. That's why cloning could be a solution to that dilemma.

We should proceed this debate 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. In 1993 the first human embryos were cloned using a technique that placed individual embryonic cells 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 is the creation of an organism that is an exact copy of another. There are different types of cloning. A basic understanding of the different types of is the key to taking an informed stance on current public policy issues and making the best personal decisions.

WHAT IS A CLONE? 27821syh95bkl9r

As per biology, a clone is a cell or an organism that is genetically identical to another cell or organism. Many simple organisms such as bacteria reproduce themselves by copying their DNA and splitting in half. The two bacteria that result from this form of asexual reproduction are genetically similar, they are clones of each other. In contrast, during the process of sexual reproduction, the nucleus of a sperm cell, which carries the father's DNA, fuses with the nucleus of an egg cell, which contains the mother's DNA. The resulting offspring carry genetic material from both parents and are not identical to either parent.

The verb ''to clone'' refers to the process of creating cloned cells or organisms. The process differs, depending on the kinds of cells used in the cloning procedure and the desired result. Usually, when scientists clone an animal, they take the nucleus of a cell (which contains chromosomes made of deoxyribonucleic acid-DNA and proteins) and place it into an egg cell (also called oocyte) from which the nucleus had been removed. The egg cell then divides to produce an embryo that develops into an animal, if the procedures work as planned.

WHAT IS HUMAN CLONING? yk821s7295bkkl

A "human clone" is a time-delayed identical twin of another person. A clone is not an exact replica of the original, but just a much younger identical twin. As with identical twins, the clone and the original being will have different set of fingerprints. Ever since Dolly's (the cloned sheep) birth in 1997 shocked an unexpecting world, Governments have been busy trying to prevent the advent of human cloning.

There is also the fear that someone would create armies of soldiers or even produce large amounts of workers. This could create lower class for clones and compromising individualities.

A "black market" of fetuses could arise from desirable donors that will want to clone themselves, i.e.: athletes, film stars, scientists and others.

Technology is not fully developed. It has a low fertility rate. In cloning Dolly, 277 eggs were used, 30 started to divide, 9 induced pregnancy, and only one survived to term (Nash).

Clones may be treated as second-class citizens. Human cloning would bring grave risks of abuses to human dignity and exploitation by unscrupulous people.

Unknown psychosocial harms with impacts on the family and society. Many see this as a violation of the uniqueness of a human life, which God has given to each of us and to no one else.


When the media report on cloning in the news, they are usually talking about only one type called reproductive cloning. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. A basic understanding of the different types of cloning is the key to taking an informed stance on current public policy issues and making the best possible personal decisions. The following three types of cloning will be discussed: (1) recombinant DNA technology or DNA cloning, (2) reproductive cloning, and (3) therapeutic cloning.

(1) Recombinant DNA Technology or DNA Cloning

The terms "recombinant DNA technology", "DNA cloning", "molecular cloning" or "gene cloning" all refer to the same process the transfer of DNA fragment of interest from one organism to a self-replicating genetic element such as a bacterial plasmid. The DNA of interest can then be propagated in a foreign host cell. This technology has been around since the 1970s, and it has become a common practice in molecular biology labs today.

Scientists studying a particular gene often use bacterial plasmids to generate multiple copies of the same gene. Plasmids are self-replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial genome. Plasmids and other types of cloning vectors are used by Human Genome Project researchers to copy genes and other pieces of chromosomes to generate enough identical material for further study.

To "clone a gene" a DNA fragment containing the gene of interest is isolated from chromosomal DNA using restriction enzymes and then united with a plasmid that has been cut with the same restriction enzymes. When the fragment of chromosomal DNA is joined with its cloning vector in the lab it is called a "recombinant DNA molecule". Following introduction into suitable host cells the recombinant DNA can then be reduced along with the host cell DNA. Bacteria are most often used as the host cells for recombinant DNA molecules but yeast and mammalian cells are also used.

(2) Reproductive Cloning

Reproductive cloning is a technology used to generate an animal that has the same unclear DNA as another currently or previously existing animal. Dolly was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current 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.

Dolly or any another animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. Mitochondria, which are organelles that serve as power sources to the cell, containing their own short segments of DNA. Acquired mutations in mitochondrial DNA are believed to play an important role in the aging process.

Dolly's success is truly remarkable because it proved that the genetic material from a specialized adult cell, such as an udder cell programmed to express only those genes needed by udder cells, could be reprogrammed to generate an entire new organism. Before this demonstration, scientists believed that once a cell became specialized as a liver, heart, udder, bone, or any other type of cell, the change was permanent and other unneeded genes in the cell would become inactive. Some scientists believe that errors or incompleteness in the reprogramming process cause the high rates of death, deformity, and disability observed among animal clones.

(3) Therapeutic Cloning

Therapeutic cloning, also called "embryo cloning", is the production of human embryos for use in research. The goal of these processes is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blatocyst. The extraction process destroys the embryo, which raises a variety of ethical concerns. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases.

In November 2001, scientists from Advanced Cell Technologies (ACT), a biotechnology company in Massachusetts, announced that they had cloned the first human embryos for the purpose of advancing therapeutic research. To do this, they collected eggs from women's ovaries and then removed the genetic material from these eggs with a needle less than 2/10,000th of an inch wide. A skin cell was inserted inside the enucleated egg to serve as a new nucleus. The egg began to divide after it was stimulated with a chemical called ionomycin. The results were limited in success. Although this process was carried out with eight eggs, only three began dividing, and only one was able to divide into six cells before stopping.



Scientists hope that one day therapeutic cloning can be used to generate tissues and organs for transplants. To do this, DNA would be extracted from the person in need of a transplant and inserted into a nucleated egg. After the egg containing the patient's DNA starts to divide, embryonic stem cells can be transformed into any type of tissue would be harvested. The stem cells would be used to generate an organ tissue that is a genetic match to the recipient. In theory, the cloned organ could than be transplanted into the patient without the risk of tissue rejection. If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced.


The Italian doctor Secerino Atinori wants to offer cloning as a treatment for infertility. Critics have pointed out that anyone who was a clone of their parents would be under unknown psychological pressures throughout their childhood. Would they feel they were living up the achievements of their "original"? And how would a woman feel about bringing up a much younger version of the person she fell in love with?


In recent years, some bereaved families have contacted scientists asking them to clone a dead child. However, even if human cloning was possible, families might be distraught to discover their new baby was not exactly like their dead older brother or sister- and the 'replacement' child might suffer feelings of inferiority about being born purely to take the place of their dead sibling.


If Mother Theresa or Einstein could be genetically reproduced, their clones might choose very different paths in life, and disappoint the people who had chosen to create them.

Cloning could do many good things for our wildlife and our economy. The process of cloning can save us a lot of money. A crop that is imported in our country could 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 better plants, cloning could lead to more profit for farmers and we could clone an abundance of trees, which would help the ecological health of our planet. Cloning is good for us as a nation and a world, to save many different types of endangered species. We would also be able to keep an animal within a controlled number.



Reproductive cloning is expensive and highly inefficient. More than 90% of cloning attempts fail to produce viable offspring. More than 100 nuclear transfer procedures could be required to produce one viable clone. In addition to low success rates, cloned animals tend to have more compromised immune function and higher rates of infection, tumor growth, and other disorders. Japanese studies have shown that cloned mice live in poor health and die early. Many cloned animals have not lived long enough to generate good data about how clones age. Appearing healthy at a young age unfortunately is not a good indicator of long term survival. Clones have been known to die mysteriously. For example, Australia's first cloned sheep appeared healthy and energetic on the day she died, and the results from her autopsy failed to determine the cause of her death.

Cloning destroys the genetic diversity of life. When everything is the same genetically then it is more likely that the entire population will be wiped out by their disease or predator. Iam Wilmut, a researcher in Roslin, Scotland says: "The more you interfere with reproduction, the more danger there is of things going wrong".


Due to the inefficiency of human cloning and the lack of understanding about reproductive cloning, many scientists and physicians strongly believe that it would be unethical to attempt to clone humans, Not only do most attempts to clone mammals fail, about 30% of clones born alive are affected with "large offspring syndrome" and other debilitating conditions. Several cloned animals have died prematurely from infections and other complications. The same problem would be expected in human cloning. In addition, scientists do not know how cloning could impact mental development. While factors such as intellect and mood may not be as important for a cow or mouse, they are crucial for the development of healthy humans. With so many unknowns concerning reproductive cloning, the attempt to clone humans at this time is considered potentially dangerous and ethically irresponsible.


It is your choice!!!!!!!!!!!!!!!

Made by:

Stoian Andra Soare Dragos

Dumitru Cristina Jinga Raluca

Dumitru Silvia Coman Corina

Herman Laura Stancu Olivia

Copyright © Contact | Trimite referat

Ultimele referate adaugate
Mihai Beniuc
   - Mihai beniuc - „poezii"
Mihai Eminescu Mihai Eminescu
   - Mihai eminescu - student la berlin
Mircea Eliade Mircea Eliade
   - Mircea Eliade - Mioara Nazdravana (mioriţa)
Vasile Alecsandri Vasile Alecsandri
   - Chirita in provintie de Vasile Alecsandri -expunerea subiectului
Emil Girlenu Emil Girlenu
   - Dragoste de viata de Jack London
Ion Luca Caragiale Ion Luca Caragiale
   - Triumful talentului… (reproducere) de Ion Luca Caragiale
Mircea Eliade Mircea Eliade
   - Fantasticul in proza lui Mircea Eliade - La tiganci
Mihai Eminescu Mihai Eminescu
   - „Personalitate creatoare” si „figura a spiritului creator” eminescian
George Calinescu George Calinescu
   - Enigma Otiliei de George Calinescu - geneza, subiectul si tema romanului
Liviu Rebreanu Liviu Rebreanu
   - Arta literara in romanul Ion, - Liviu Rebreanu

Scriitori romani