Dear Dr. Universe,
How do we clone things?
Raphael, 8, São Paulo, Brazil
From frogs to sheep to cats, humans have learned to clone all kinds of organisms. Like you, I was curious how it all works, so I talked to my friend Jon Oatley, a researcher at Washington State University.
First, he told me that mammals — like you and me — are made up of billions of building blocks called cells. Other organisms, like amoebas, are just a single cell.
Inside each cell is a nucleus, which is like a small envelope that protects something very important: DNA.
DNA holds the code to all sorts of different traits, such as hair color, eye color and skin color. This genetic information can be passed down from grandparents to parents to their offspring.
One type of reproduction requires both the DNA from inside a sperm cell and inside an egg cell for an organism to start developing. When these two cells come together, they form a single cell and then start multiplying. These cells make up an embryo, the earliest stage of development.
But when we want to clone something, we don’t need DNA from both a sperm cell and an egg cell. Instead, the DNA comes from a single nonreproductive cell, called a somatic cell. It might be a cell from muscle, brain or even skin.
Scientists can pull out DNA from inside one of those cells and put it into the empty shell of an organism’s egg cell. With a zap of electricity, the cells start multiplying and form an embryo.
After the embryo stage comes the fetus stage, and then finally the offspring. The offspring, or clone, will have the same DNA as the original organism.
“We can do this in essentially all mammals,” Oatley said.
Even though the DNA is identical, that doesn’t mean a clone will be a perfect carbon copy of the original, he adds. For instance, the first cat clone had the same DNA as her donor cat Rainbow. Rainbow was a calico cat with orange, black, and white fur. But Cc, the clone, was grey and white.
A clone may look different than its donor because some traits occur randomly as the clone develops in the womb. The environment where a clone lives can also make the clone look or behave differently than its donor, too.
Cloning is a tool scientists can use in the lab to help us better understand genetics. It can help us identify genes and improve the traits of different food products, which is especially important for feeding Earth’s growing population. Cloning also helps us gain a better understanding of how genes work and when those genes might be the source of health problems.
Oatley said it’s great to hear that you are already curious about the world of life sciences, Raphael. Who knows, maybe one day you can help us learn more about the way genes work and how DNA shapes life on our planet.