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What is palindromic DNA and why isn't every complementary strand palindromic?

I know AGCT is palindromic, but what is an example of a strand that isn't?

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    $\begingroup$ I'm voting to close this question as off-topic because it seems to be more about biology than pure chemistry. Better move to Biology.SE $\endgroup$ – Jori Apr 1 '15 at 19:06
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    $\begingroup$ It came from a biochem course. I was eavesdropping in some friends when they were studying. $\endgroup$ – Moshe Apr 1 '15 at 19:23
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    $\begingroup$ This is a chemistry question, not a biology question. DNA is a complex heteropolymer and whether or not comething is a palindrome can affect the polymer's reactivity and behavior. Also, since when have questions needed to be about "pure" chemistry to be on topic around here? :-) $\endgroup$ – Curt F. Apr 1 '15 at 22:31
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A palindromic stretch of DNA is a strand whose reverse complement is itself. So 5'-AAAT-3' is not palindromic. It's reverse complement is 5'-ATTT-3'. Those two pieces of DNA are not identical. However, 5'-GGATCC-3' is palindromic, because the reverse complement is identical.

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It has nothing to do with the complementarity (of the other strand).

Try this to figure out whether some sequences are palindromic:

#!/usr/bin/env python3
def is_palindromic(seq):
    translation_table = str.maketrans('ACGT', 'TGCA')
    translation = seq.translate(translation_table)
    #print(seq, translation[::-1])
    return seq == translation[::-1]

is_palindromic('GATTACA')
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