(Sing to the tune of Mary Had a Little Lamb)
Ian made a little lamb, little lamb, little lamb.
Ian made a little lamb and Dolly was her name.
When she grew, she was just like mom
Just like mom, just like mom.
Why was she just like mom?
Their DNA’s the same!
A Sheep Named Dolly
In 1997, a 7-month-old sheep named Dolly became a celebrity. Dr. Ian Wilmut, a Scottish scientist, announced to the world that he had created her using a procedure called cloning. Cloning is a method that scientists use to produce a genetic copy of another individual. In other words, Dolly was a clone of her mother.
Well, actually, Dolly had three mothers. One mother gave Dolly her DNA, one mother supplied an egg, and the third mother, her surrogate mother, gave birth to her.
Normally, an animal gets half of its DNA from its mother and half from its father. Dolly was an identical twin of the mother who gave her her DNA. But Dolly was six years younger.
However, Dolly and her mother were not identical in every way. Since Dolly and her “DNA mother” had different experiences, they were different in many ways. Like human twins, clones have unique personalities.
It took scientists 277 tries to succeed in cloning Dolly. To make her, Dr. Wilmut used a complicated method called “nuclear transfer.” In this method, scientists remove a nucleus from one cell and transfer, or move, it to a different cell.
Photos: Dr. Ian Wilmut and Dolly; Dolly and her birth mother, courtesy of the Roslin Institute; Illustrations: Clay Meyer