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Scientists have cloned an endangered horse using cells preserved for 40 years. Some think cloning could help prevent more species from dying out. But what is cloning? And how does it work? What are clones? They are genetically identical individuals. The term "cloning" describes a process that produces an exact copy of a biological being. The copy - which has the same DNADeoxyribonucleic acid is the material in an organism that carries genetic information. as the original - is then referred to as a clone. It may be surprising to learn that cloning takes place all the time - naturally. Some plants and single-celled organisms produce genetically identical offspring through a process called asexual reproductionA form of reproduction that does not involve sex cells in the case of animals, or fertilisation in the case of plants.. Over the past 70 years, scientists have developed various methods of artificial cloning. How does artificial cloning work? The simplest way to make a clone is to take a cutting from a plant and place it in compost. In a few weeks, roots will begin to sprout. With animals, cloning is more complicated. The most successful process is known as somatic cellA cell with two sets of chromosomes. Sexual reproduction normally requires a sperm and an egg, both with one set of chromosomes. nuclear transferNuclear means relating to a nucleus. A nuclear transfer describes the process of the nucleus being removed from the somatic cell and placed in a different cell.. Scientists collect two donor cells - one is a somatic cell from the animal to be cloned. The other is an unrelated egg cellIn mammals, this is also known as an ovum, which comes from the Latin word for egg. that has had its DNA removed. They then remove the nucleusWhere the DNA of a cell is stored. from each cell, placing the DNA from the somatic cell in the empty ovum. This then grows into an embryoA fertilised egg that is developing into a foetus., and eventually into an exact copy of the original animal. What was the first animal ever cloned? A frog. In 1952, researchers successfully formed a new tadpole after replacing the nucleus from an egg with the nucleus from an already developing embryo. Over the following years, scientists used the same technique to create clones of mice, fish and cattle. In 1996, the first mammal was cloned through somatic cell nuclear transfer. Although Dolly the sheep died from health complications at the age of six, she remains one of the most famous clones of all time. So, why is the latest clone special? Because his somatic cell donor is dead. In fact, this Przewalski's horse is the exact clone of a stallion that died over 20 years ago. Luckily, the cells needed to create the clone were safe in what's known as the Frozen Zoo. This is a laboratory at San Diego Zoo where millions of cells belonging to over a thousand endangered species are kept in suspended animationWhen a living thing temporarily stops most of its normal functions — for example, a hibernating animal. in liquid nitrogen. Kurt Benirshke founded the zoo in 1972, hoping that it would one day be able to help with conservationThe practice of protecting plant and animal species and their habitats.. This new clone widens the gene pool of the endangered species, hopefully ensuring their survival. Forty-five years on, the successful creators of the Przewalski's foal have named him Kurt. Could we bring back long-dead species? Possibly! As technology improves, many scientists are working on ways to revive animals that disappeared hundreds or thousands of years ago. Teams around the world are hoping to create the first living, breathing woolly mammoth clone using remains of the ancient animal. But the plans have their critics; many worry that such animals would struggle to survive, or disrupt modern ecosystemsComplex networks of living things that rely on each other to survive., putting other animals and people in danger. Will we ever clone humans? At the moment, nobody is seriously trying to do this. Most people consider cloning humans unethical, at the very least because the cloning process has often created animals with health problems. These would be more likely to occur in a human because primatesThe order of mammals that includes humans, alongside apes like chimpanzees and gorillas. have proven especially difficult to clone. However, some scientists are working on using cloning technology to create stem cells. These "master" cells are the basis for all the body's organs, blood, bones etc. and could help to repair dysfunctional or injured tissue - a tremendous breakthrough if realised.KeywordsDNA - Deoxyribonucleic acid is the material in an organism that carries genetic information.

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