There are two main biological principles that are needed to know to understand this article. With replication of DNA everything has to be in order, the genes have to be in the right place at the right time. If one enzyme does not give the right signal at the right time, replication will stop and the cell will stop functioning. Secondly, you must understand the process of the development of a normal fertilized egg to understand the cloning of an animal. After the embryo is formed by meiosis the next step is mitosis.
Mitosis is where the DNA is duplicated to form homologous pairs of chromosomes.
The cell then separates or pulls apart the chromosomes, and then the two daughter cells are formed. This process happens all the time in the cells of every animal. Now we can look at nuclear transfer. The scientists take an egg cell out of an animal and an embryo out of another. They remove the chromosomes or DNA from the egg cell and replace them with the individual cells from the embryo.