"Hi! Gene back to tell you all about cloning. It's all over the news with identical sheep (as if they don't look enough alike already) and tomatoes that stay fresh on the shelves for a longer time.
The words 'cloning' and 'genetic engineering' are often used by people as though they mean the same thing.
Well, they have an overlapping meaning that becomes clear when we look through history.
"Genetic engineering, in its broadest definition, means to manipulate a species so that a particular trait is increased in the population. A trait is how an organism looks or acts or what it does. Brown eyes is a trait. Flying in circles is a trait. Climbing trees is a trait.
"The earliest forms of genetic engineering occurred on farms, where most people on earth lived at the time. They managed to do this by selecting seeds from plants that maybe had more fruit production or tastier leaves than other plants of its type.
"They planted those seeds and grew plants that had more of the favorable traits. Then they chose to save the seeds from the best of that lot to sow the next year. So, year by year, the farmers produced better and better crops. This type of activity probably has been going on since mankind first settled in villages and began making a life for themselves in one location, about 12,000 years ago!
"The same sort of thing would have also happened with animals. By eating the animals that didn't have favorable traits, like pulling a large load, and letting the animals with the favorable traits reproduce, herds and flocks would slowly develop more and more traits that humans found useful. It was thousands of years before mankind figured out how plants and animals reproduce themselves. With this knowledge, people could pollinate plants by hand or pen a pair of animals together in order to deliberately cause an increase in a favorable trait.
"It was only in the last 250 years that scientists began figuring out about chromosomes
and genes and the role they play in the way one generation passes its traits on to the next. And its only been in the last 30 years that scientists have been able to cut out specific genes from one organism and put them in another.
"It is this 30 year old technology that is described by the narrow definition of genetic engineering. Mankind has long been able to have a deliberate impact on the world around him. He now possesses the tools to deliberately impact himself. Some people are afraid of what might be done with that power.
"The word 'clone' was first used as a noun to describe a population of cells that reproduced themselves faithfully. A clone produces cells that not only have the same chromosomes, but which turn on the same genes, turn off the same genes, and therefore look identical, act the same, and do the same things.
"If you took one bacterium and gave it food, it would reproduce itself until the food ran out. The bacteria produced would all be identical and form what is called a clone or a 'cell line'.
"With plants and animals this process is more difficult because of the many, many types of cells that compose these organisms. Most of the cells do reproduce themselves very slowly, if at all, in an adult. Cancer cells are an exception to this, reproducing themselves rapidly. Cancer cells are natural clones and were the first human cells isolated and grown in laboratories. All the cells of a cell line produce cells which look identical and act the same way and do the same things.
"The word 'cloning' has come to mean using genetic engineering techniques to produce either lines of identical looking and acting cells or genetically identical animals or plants. When we speak of cloned animals, we do not expect them to act alike; just have identical genes. Twins are nature's clones, and we know they do not act alike or have the same personality at all.
"Let's look at some genetic engineering techniques and see what can be produced with them."
CLONING: For Parents & Teachers
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