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The causes of mutations
Mutations happen for several reasons.
- DNA fails to copy accurately
Most of the mutations that we think matter to
evolution are "naturally-occurring." For example, when a cell divides, it makes a
copy of its DNA — and sometimes the copy is not quite perfect. That small
difference from the original DNA sequence is a mutation.
External influences can create mutations
 Mutations can also be caused
by exposure to specific chemicals or
radiation. These agents cause the DNA to break down. This is not necessarily
unnatural — even in the most isolated and pristine environments, DNA breaks
down. Nevertheless, when the cell repairs the DNA, it might not do a perfect job
of the repair. So the cell would end up with DNA slightly different than the
original DNA and hence, a mutation. |
