How is Cloning Done?
There are two ways that cloning can be done. The two ways are artificial embryo twinning and somatic cell nuclear transfer. When the sperm and egg cell first combine, it becomes a zygote, which develops into an embryo. An embryo is made of cells with two sets of chromosomes, and it is the result of both methods of cloning.
What is Artificial Embryo Twinning?
Artificial embryo twinning is similar to the way twins are created. Twins occur when the fertilized egg divides into two cells and the cells separate (normally they stay together). Then, each cell grows on its own into a twin. Artificial embryo twinning is done in a lab by scientists, but it uses the same method. The scientists separate the cells purposefully, and then put the embryo into a mother so that the embryo can grow and be born.
Below: A picture of an embryo from Wikipedia
Below: A picture of an embryo from Wikipedia
What is Somatic Cell Nuclear Transfer?
Somatic cell nuclear transfer is another way that cloning can be done. Dolly the sheep, one of the most famous examples of cloning, was cloned through somatic cell nuclear transfer. The process starts with a somatic cell. A somatic cell is a body cell, or any cell that is not a sex cell. In somatic cell nuclear transfer, the nucleus from a somatic cell is taken. Then, the nucleus is put into an egg cell which has had its nucleus removed. The egg cell acts just like a zygote, and develops into an embryo. Like artificial embryo twinning, the embryo is then put into a mother so that the embryo can grow and be born. The sperm and egg cell each only have one set of chromosomes, and when they combine the zygote has two sets, one from the mother and one from the father. However, all of the somatic, or body, cells have two sets. Therefore, when the nucleus is transferred, the egg cell has two sets of chromosomes and acts like a fertilized egg.
Below: Diagram of Somatic Cell Nuclear Transfer from Wikipedia
Below: Diagram of Somatic Cell Nuclear Transfer from Wikipedia