Here's why:
* Somatic cells are the cells that make up the body, unlike germ cells (sperm and egg). They have the same genetic information as the original fertilized egg.
* Nuclear transfer experiments, such as the one that produced Dolly the sheep, involve taking the nucleus from an adult cell and placing it into an egg cell that has had its own nucleus removed.
* The resulting organism develops with all the characteristics of the donor animal, proving that the nucleus contains the complete genetic instructions for development.
This experiment fundamentally changed our understanding of development. It showed that:
* Differentiation (the process of cells specializing into different types) doesn't involve loss of genetic information, but rather the selective expression of specific genes.
* Adult cells retain the potential to develop into any cell type in the body, a concept known as totipotency.
In summary, the ability to use an adult cell's nucleus to create a new organism highlights the central role of the genetic information in the nucleus in driving development and cell differentiation.
