There is a general feeling that palindromes are frivolous
curiosities in number theory which find no real world applications
other than in recreational games. This is not true.
The very building blocks of life, i.e. DNA sequences, make use of
palindromes. A DNA sequence consists of two complementary strands
coiled in a double helical structure. DNA researchers found that
some enzymes have the ability to recognise palindromes and
cut DNA-sequences at these specific sites. Does this
qualify Nature as the first user of palindromes ? A typical
staggered cut made by an enzyme in a double helix is shown
in figure 1:
staggered cut made by
---GAATTC-- --G! AATTC-----------
---CTTAAG--- ---CTTAA ! G----------
\================== Fig.1 =========================/
DNA researchers have found many such enzymes for different types of
staggered cuts based on the recognition of palindromic pairs. They are
now able to cut and splice DNA sequences almost at will thus
contributing greatly to the present phenomenal progress in this
discipline. Note that in figure 1, after the staggered cut, the two ends
will each have a free stub sticking out. These free stubs will look for
palindromic stubs to dock in a biochemical soup full of DNA fragments.
Remember, palindromes are unique pairs.