What goes on in that 3% it DNA, and what similarities do we share in the 97%?
In: Biology
Differences aren’t just from the DNA being different, but from how the DNA is expressed – also called the phenotype.
Basically, we think of living organisms as having traits defined by their DNA, but really their traits are defined by *how their DNA is expressed*. There are a lot of ways this can vary from organism to organism. For example, your body may produce more or less of a protein based on a reaction to outside stimuli, and that protein could create different observable characteristics, but there is no change in the underlying DNA.
Identical twins (not fraternal twins), for example, usually have the same DNA. But they can have differences in how that DNA is expressed, which can result in differences in physical appearance, behavior, and even differences in health. Some of this can be caused by translation errors of the DNA (errors that result in the DNA being changed), but much of it will be caused by differences in environment that result in different biological responses.
When you reach a point where you actually *are* changing the underlying DNA, the changes start to become much more dramatic. This is why children can look so different from their parents (even though they often have some similar characteristics). By changing the DNA, even a small amount, you can make huge changes in the phenotype expression. Some of this can come from the fact that areas of DNA that weren’t used at all in one organism are now used by the new organism to produce proteins. These proteins don’t exist in the first organism, but could cause dramatic changes in appearance, behavior, or function in the new organism.
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