Therapeutic cloning involves creating a cloned embryo for the sole purpose of producing embryonic stem cells with the same DNA as the donor cell. These stem cells can be used in experiments aimed at understanding disease and developing new treatments for disease.
To date, there is no evidence that human embryos have been produced for therapeutic cloning. The richest source of embryonic stem cells is tissue formed during the first five days after the egg has started to divide. At this stage of development, called the blastocyst, the embryo consists of a cluster of about cells that can become any cell type.
Stem cells are harvested from cloned embryos at this stage of development, resulting in destruction of the embryo while it is still in the test tube. Researchers hope to use embryonic stem cells, which have the unique ability to generate virtually all types of cells in an organism, to grow healthy tissues in the laboratory that can be used replace injured or diseased tissues.
In addition, it may be possible to learn more about the molecular causes of disease by studying embryonic stem cell lines from cloned embryos derived from the cells of animals or humans with different diseases.
Finally, differentiated tissues derived from ES cells are excellent tools to test new therapeutic drugs. Many researchers think it is worthwhile to explore the use of embryonic stem cells as a path for treating human diseases. However, some experts are concerned about the striking similarities between stem cells and cancer cells. Both cell types have the ability to proliferate indefinitely and some studies show that after 60 cycles of cell division, stem cells can accumulate mutations that could lead to cancer.
Therefore, the relationship between stem cells and cancer cells needs to be more clearly understood if stem cells are to be used to treat human disease. Gene cloning is a carefully regulated technique that is largely accepted today and used routinely in many labs worldwide. However, both reproductive and therapeutic cloning raise important ethical issues, especially as related to the potential use of these techniques in humans.
Reproductive cloning would present the potential of creating a human that is genetically identical to another person who has previously existed or who still exists. This may conflict with long-standing religious and societal values about human dignity, possibly infringing upon principles of individual freedom, identity and autonomy. However, some argue that reproductive cloning could help sterile couples fulfill their dream of parenthood.
Others see human cloning as a way to avoid passing on a deleterious gene that runs in the family without having to undergo embryo screening or embryo selection. Therapeutic cloning, while offering the potential for treating humans suffering from disease or injury, would require the destruction of human embryos in the test tube. Consequently, opponents argue that using this technique to collect embryonic stem cells is wrong, regardless of whether such cells are used to benefit sick or injured people.
Cloning Fact Sheet. Do clones ever occur naturally? What are the types of artificial cloning? How are genes cloned? How are animals cloned?
What animals have been cloned? Have humans been cloned? Do cloned animals always look identical? What are the potential applications of cloned animals? It is used to amplify a particular DNA fragment containing target genes. Apart from the genes coding sequences , it is also used in making multiple copies of promoters, non-coding sequences, and randomly fragmented DNA.
The general steps in molecular cloning are as follows:. This is then followed by ligation wherein the DNA fragments are glued together to achieve the desired sequence. Transfection is when the newly formed pieces of DNA are inserted into the cell. The transfected cells are then cultured. Screening or selection proceeds by identifying the cells with the new DNA.
Cloning a cell means deriving a population of cells from a single cell. In single-celled organisms such as bacterial cells and yeast cells, the process entails getting a sample and then inoculating it to the culture medium.
How about cloning a cell from a multicellular organism? This is rather a more complex procedure involving the use of cloning cylinders rings. In essence, the cloning cylinder a sterile polystyrene ring is dipped in grease and then placed over an individual colony where cloned cells inside the ring can eventually be produced and subsequently collected for transferring into a new vessel. Somatic-cell nuclear transfer is a form of cloning where stem cells are cloned for research or for therapeutic purposes, but not for reproduction.
The stem cells are cloned and harvested for studying human diseases and thereby find a cure or understand the pathobiology of the disease.
So far, this technique has been used for agriculture and for cloning animals, such as sheep, cattle, goats, and pigs. It is therefore seen as a solution to save endangered species from extinction.
Organism cloning also called reproductive cloning refers to the procedure of creating a new multicellular organism that is genetically identical to another. As already mentioned, cloning is a form of asexual reproduction. No sex cells gametes are involved in the process.
Because there is no need for a mate, the parent organism reproduces relatively faster than organisms that reproduce sexually. Nevertheless, the disadvantage of asexual means, including cloning, is the decreased genetic diversity in the species. The low genetic variation could essentially make the offspring be similarly predisposed to environmental stressors whereby their parent is susceptible.
Twinning happens in the first days after egg and sperm join, while the embryo is made of just a small number of unspecialized cells. Each half of the embryo continues dividing on its own, ultimately developing into separate, complete individuals. Since they developed from the same fertilized egg, the resulting individuals are genetically identical. Artificial embryo twinning uses the same approach, but it is carried out in a Petri dish instead of inside the mother.
A very early embryo is separated into individual cells, which are allowed to divide and develop for a short time in the Petri dish. The embryos are then placed into a surrogate mother, where they finish developing.
Again, since all the embryos came from the same fertilized egg, they are genetically identical. Somatic cell nuclear transfer SCNT , also called nuclear transfer, uses a different approach than artificial embryo twinning, but it produces the same result: an exact genetic copy, or clone, of an individual.
This was the method used to create Dolly the Sheep. Somatic cell: A somatic cell is any cell in the body other than sperm and egg, the two types of reproductive cells. Reproductive cells are also called germ cells. In mammals, every somatic cell has two complete sets of chromosomes, whereas the germ cells have only one complete set. Nuclear: The nucleus is a compartment that holds the cell's DNA. The DNA is divided into packages called chromosomes, and it contains all the information needed to form an organism.
It's small differences in our DNA that make each of us unique. Transfer: Moving an object from one place to another. Tyson Brown, National Geographic Society. National Geographic Society.
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Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. But the first formal genetic study was undertaken by a monk named Gregor Mendel in the middle of the 19th Century. Mendel bred peas and noticed he could cross-pollinate them in certain ways to get green or yellow seeds.
Today, the field of genetics is breaking new ground searching for new ways to treat disease or develop crops more resistant to insects or drought. Empower your students to learn about genetics with this collection of resources.
Biotechnology is the use of living systems and organisms to create new technologies. On the simpler end of the spectrum, baking bread with yeast is an example of this interdisciplinary science.
On the more complex side, genetic engineering, biochemistry, and molecular biology are pushing boundaries in an effort to treat illnesses, develop new biofuels, and grow plants more efficiently to feed more people.
Use these resources to dig into biotechnology with your students.
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