Methods of Cloning
- DNA cloning is the process of copying DNA from one cell into the genetic material of another cell. Enzymes are used to split the useful section of DNA from the rest of the first cell's genetic material. The section of DNA is then introduced into a self-replicating structure, for example a bacterial plasmid, which has had a similar section cut out from its DNA. The bacteria then replicates the DNA as it reproduces, creating many copies of the desired section. This technique is mostly used when scientists want to study a particular section of DNA and want to have lots of copies on hand.
- Reproductive cloning is a process that creates an animal that has almost exactly the same genetic material as another animal. Scientists use a process called "somatic cell nuclear transfer" to introduce the genetic material of an adult animal into a egg cell. Once the egg has been treated to stimulate division, it is implanted in the uterus of a female animal of the same species. The child is then born by normal means. While science has succeeded in creating animals that have almost exactly the same genetic material as their gene donor, cloned animals have tended to have a significantly reduced life expectancy.
- Therapeutic cloning, which is also known as "embryo cloning," is a process that creates human embryos for scientific purposes. Therapeutic cloning does not create genetically identical human beings but is used to harvest stem cells.In this process, an egg is allowed to divide for five days, forming what is called a blastocyst, before the stem cells are harvested. Since this technique is considered ethically controversial, scientists are working to discover ways to create stem cells that do not involve the use of genetically viable human embryos, but have so far had little success.
