In many ways, cloning a monkey is just like cloning any other animal. Basically, all a scientist needs is some monkey DNA, a monkey egg and some experience with very expensive equipment.
First, a monkey cloner needs some monkey DNA. This makes sense since DNA contains all of the instructions for making a living organism. In fact, it is even "written" in a code that uses four lettersA, G, C, and T. So monkey DNA has the instructions for making a monkey.
Fusing an egg without a
nucleus with an adult cell
makes a clone.
But scientists can't just read these instructions and create a new monkey. Only a cell can read all of the DNA of an animal all at once. And the cell can't do this with the kind of naked DNA you can get out of a strawberry at home
. A cell needs DNA in its natural environmentin the nucleus of a cell.
So the first step is really to get a monkey nucleus. The second step is to remove the nucleus from a monkey egg and to replace it with the adult monkey nucleus. What scientists actually do most of the time is to fuse the adult cell with the egg that is missing its nucleus. But the end result is the samean egg with a new nucleus.
So now the scientist can just grow the fused egg up and make a clone, right? After all, every cell has the same DNA so all the instructions for making a monkey are now in the egg. Except that it won't work because all DNA is not the same.
All the letters of DNA are the same between one cell and another in any single animal. But the DNA is used differently in different kinds of cells. And the cells "mark" up DNA differently
depending on how they use it. These marks affect how the DNA is read when it is moved to a different cell.
So the DNA of a skin cell is marked differently than the DNA of a liver cell, or a muscle cell, or any other kind of cell. To successfully clone an animal, these markings need to be changed from an adult cell to that of a fertilized egg. And this is what the group in Oregon successfully did.
They removed the nuclei from 304 eggs and fused each egg to an adult monkey skin cell. Of these 304 eggs, thirty five were successfully made into an early embryo called a blastocyst.
The scientists could have then implanted these blastocysts into a surrogate mother to try to grow a new monkey. But that wasn't the purpose of the research. Their purpose was to make embryonic stem cells.