You will hardly meet a person who has never heard about Dolly the sheep who is regarded to be the first cloned animal. The experiments of the team of Scottish scientists had made 276 attempts of cloning before they finally were able to create a clone of a six-year-old sheep. The clone of the sheep is known to the world as Dolly.
Even if you have heard about this story, how much do you know about cloning? This article will provide you with interesting facts which will give you insights into the technology of cloning.
What is cloning?
As the name suggests a clone is an identical copy. While people are aware of cloned animals, many do not know that cloning is also used for just fragments of bodies of living organisms such as tissues, organs or cells. Thus, a clone is not necessarily an exact copy of an animal or a human being. It is an exact copy of a biological material.
One of the most popular types of cloning which is used nowadays is molecular cloning and it is the technology widely used for creating genetically modified organisms. In this case, scientists first extract particular genes form a living organism that they would like to add to another species. The new gene is transmitted to another organism via bacterium plasmids. A bacterium with a new DNA is cloned giving even more plasmids with a new genetic code which can be then used successfully for creating more genetically modified organisms.
As the name suggests, therapeutic cloning is used for medical research. For this purpose scientists are using the cells for initiating the development of an embryo, however, the growth of the organism is stopped at the stage of a blastocyst. Usually this type of cloning is used for creating stem cells which are used in various experiments. For example, the stem cells of human or animals can be used for learning about mutations and genetic diseases. Another popular field of research is growing entire organs for transplantation.
As you can imagine, reproductive cloning is used for cloning entire organisms. The technology used for this purpose is the same as the one used for therapeutic cloning, however, this time the growth of an embryo is not stopped. It is transported to the uterus of an animal of the same species which allows the embryo to grow into a developed organism.
Unlike a popular belief, Dolly was not the first cloned animal, whereas the research of this technology started at the end of the 19th century. In the 1885 there was a successful attempt of dividing an two-cell embryo of a sea urchin which gave twins. In 1902, a similar method was applied to a salamander which gave two clones of one embryo.
The first mammals were cloned in 1984 and they were actually sheep.
Which animals can be cloned?
There were many animals cloned after Dolly. Wolves, mice, rats, cats, cows, deer, horses, dogs, pigs, rabbits and many others were cloned successfully.
Yet, for some reasons its turned out that cloning of monkeys and primates is not thus simple as in the case of other mammals. It took scientists 10 years after the creation of Dolly to finally be able to grow the stem cells of a monkey. Even more ten years of research had been spent before Chinese scientists were finally able to clone a complete organism of a monkey.
One of the popular question many people have is the possibility of cloning extinct animals.
Needless to say, a perspective of cloning animals which became extinct a long time ago seems to be very exciting. How about cloning dinosaurs?
Yet, the problem in cloning such animals is actually the fact they are extinct. The remains of dinosaurs people have access today do not have a complete genetic code which is needed for cloning. The code is broken and it has many missing parts. Since the scientists do not know what this code is supposed to be in the first place they just have to rearrange and fill it like puzzles using other related animals as a referential material. Certainly, these animals are not a good referential material since they differ from their extinct predecessors a lot. This gives very poor chances that the outcome will give real dinosaurs.
For some extinct animals this task can be easier. For instance, the frozen remains of mammoth which are regularly found in the ice have well-preserved genetic code. This gives more chances for successful cloning, however, in this case scientists will face another problem. As you now know, a clone needs a surrogate mother which has to be of the same species. Otherwise, the result of cloning will not give you a real mammoth. The animal will be a hybrid.
Of course, there are no real mammoth now, so scientists will need elephants for carrying the mammoth embryos. Undeniably, this will alternate the clone making it different from real mammoths.
Even if scientists were able to reproduce exact clones of extinct animals, genetic diversity is needed for creating a population which is impossible with clones.