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Example research essay topic: Adult Dna Cloning Human Cloning Technology - 1,788 words

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The possibility of human cloning was raised when Scottish scientists, led by Dr. Ian Wilmut at the Roslin Institute, created the much-celebrated sheep "Dolly." Being the first mammal ever cloned this aroused worldwide interest and concern because of its scientific and ethical implications. The feat, cited by Science Magazine as the breakthrough of 1997, also generated uncertainty over the meaning of "cloning" -- an umbrella term traditionally used by scientists to describe different processes for duplicating biological material. Since this creation, mice, goats, cows and pigs have been successfully cloned around the world. This has made human cloning a real possibility. Cloning is the production of one or more individual plants or animals that are genetically identical to another plant or animal.

It is different from natural fertilisation which is "sexual" reproduction that occurs when a sperm fertilizes an egg. In normal fertilisation the developing embryo (and person) has the genetic makeup or DNA of both parents 23 chromosomes from the female and 23 from the male. The embryo is the unique human organism with a novel genetic makeup having the full potential to develop to adulthood. Current definitions define "embryo" as follows: the term 'human embryo or embryos includes any organism that is derived by fertilisation, parthenogenesis, cloning, or any other means from one or more human gametes or human diploid cells. Figure 1: Comparing cloned embryos with fertilized embryos Source: Available from URL: web basics. htm#cloning (Accessed Sunday 15 th August 2004) 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 three main types of cloning are: 1. Embryo cloning 2.

Reproductive cloning 3. Therapeutic cloning Embryo cloning Embryo cloning might be more accurately called "artificial twinning", because it simulates the mechanism by which twins naturally develop. It involves removing one or more cells from an embryo and encouraging the cell to develop into a separate embryo with the same DNA as the original. It has been successfully carried out for years on many species of animals.

Some very limited experimentation has been done on human embryos. Nature itself is the greatest cloning agent. In about one of every 75 human conceptions, the fertilized ovum splits for some unknown reason and produces monozygotic (identical) twins. Each has a genetic makeup identical to the other. In cloning, this same operation is done intentionally in a laboratory. Figure 2: Cloning or Asexual Reproduction Source: The Center for Genetics and Society, Human Cloning and Genetic Modification: The Basic Science You Need to Know [online] Available from URL: web (Accessed Sunday 15 th August 2004) Procedure Human embryo cloning starts with a standard in vitro fertilization procedure.

Sperm and an egg cell are mixed together on a glass dish. After conception, the zygote (fertilized egg) is allowed to develop into a blastula (a hollow mass of cells). The zygote divides first into two cells, then four, then eight A chemical is added to the dish to remove the "zona pellucid a" covering. This material provides nutrients to the cells to promote cell division.

With the covering removed, the blastula is divided into individual cells which are deposited on individual dishes. They are then coated with an artificial zona pellucid a and allowed to divide and develop. The experiment by Sillman et al. showed that the best results could be obtained by interrupting the zygote at the two cell stage. Many of these pairs of zygotes were each able to develop to the 32 cell stage, but stalled at that point.

They might well have had the potential to develop further and even mature into a viable fetus, except that the original ovum was defective and would have died anyway. For ethical reasons, the researchers had selected embryos which had no possibility of ever maturing into fetuses, and thus becoming newborn babies. Reproductive Cloning Reproductive cloning is a technology used to generate an animal that has the same nuclear 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'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. Procedure With the exception of the sperm and egg, every cell in the body contains all of the genetic material in its DNA to theoretically create an exact clone of the original body. But cells have been "biochemically programmed to perform limited functions. " The other functions are turned off. Most scientists had believed that such differentiated cells could not be reprogrammed to be capable of behaving as a fertilized egg. In the case of the sheep "Dolly", a cell was taken from the mammary tissue of a mature 6 year old sheep while its DNA was in a dormant state.

It was fused with a sheep ovum which had had its nucleus removed. The "fertilized" cell was then stimulated with an electric pulse. (See Figure 3) Out of 277 attempts at cell fusion, only 29 began to divide. These were all implanted in ewes. Thirteen became pregnant but only one lamb, Dolly, was born. Figure 3: The cloning process for the sheep Dolly Source: Available from URL: web basics. htm#cloning (Accessed Thursday 12 th August 2004) Therapeutic cloning This is a procedure whose initial stages are identical to adult DNA cloning.

However, the stem cells are removed from the pre-embryo with the intent of producing tissue or a whole organ for transplant back into the person who supplied the DNA. The pre-embryo dies in the process. The goal of therapeutic cloning is to produce a healthy copy of a sick person's tissue or organ for transplant. This technique would be vastly superior to relying on organ transplants from other people. The supply would be unlimited, so there would be no waiting lists.

The tissue or organ would have the sick person's original DNA; the patient would not have to take immunosuppressant drugs for the rest of their life, as is now required after transplants. There would not be any danger of organ rejection. Figure 4: Human Therapeutic Cloning Source: Advanced Cell Technology, Inc. Worcester, Massachusetts, 2004, Human therapeutic cloning [online] Available form URL: web report cloning 01. html (Accessed Tuesday 17 th August 2004) Procedure 1. Take a woman's ovum, and remove its DNA.

This converts it to a form of human life into what is basically a factory for creating a pre-embryo. 2. Remove the DNA from a cell taken from a human, and inserting it into the ovum. 3. Giving the resulting ovum an electrical shock to start up its embryo making operation. In a small percentage of cases, a pre-embryo will be formed. 4. The pre-embryo is allowed to develop and produce many stem cells.

So far, the procedure is identical to that used in adult DNA cloning. However, the pre-embryo is not implanted in a woman's womb in order to try to produce a pregnancy. 5. Stem cells are removed from the pre-embryo; this results in its death. 6. The stem cells would be encouraged to grow into whatever tissue or organ is needed to treat the patient. Stem cells are a unique form of human cell that can theoretically develop into many organs or body parts. 7.

The tissue or organ would be transplanted into the patient. Benefits of Cloning There are many ways in which cloning is expected to benefit mankind. Below is a list that is far from complete. Rejuvenation. Dr.

Richard Seed, one of the leading proponents of human cloning technology, suggests that it may someday be possible to reverse the aging process because of what we learn from cloning. Human cloning technology could be used to reverse heart attacks. Scientists believe that they may be able to treat heart attack victims by cloning their healthy heart cells and injecting them into the areas of the heart that have been damaged. There has been a breakthrough with human stem cells.

Embryonic stem cells can be grown to produce organs or tissues to repair or replace damaged ones. Skin for burn victims, brain cells for the brain damaged, spinal cord cells for quadriplegics and paraplegics, hearts, lungs, livers, and kidneys could be produced. By combining this technology with human cloning technology it may be possible to produce needed tissue for suffering people that will be free of rejection by their immune systems. Conditions such as Alzheimer's disease, Parkinson's disease, diabetes, heart failure, degenerative joint disease, and other problems may be made curable if human cloning and its technology are not banned.

Infertility. With cloning, infertile couples could have children. Despite getting a fair amount of publicity in the news current treatments for infertility, in terms of percentages, are not very successful. One estimate is that current infertility treatments are less than 10 percent successful. Couples go through physically and emotionally painful procedures for a small chance of having children. Many couples run out of time and money without successfully having children.

Human cloning could make it possible for many more infertile couples to have children than ever before possible. Defective genes. The average person carries 8 defective genes inside them. These defective genes allow people to become sick when they would otherwise remain healthy. With human cloning and its technology it may be possible to ensure that we no longer suffer because of our defective genes.

Down's syndrome. Those women at high risk for Down's syndrome can avoid th...


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