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.
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External influences can create 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.