I'm writing a program in which I can Reverse the sequence and Replace all As with Ts, all Cs with Gs, all Gs with Cs, and all Ts with As. the program is to read a sequence of bases and output the reverse complement sequence. I am having trouble to do it so can anyone please help me with this by having a look on my code:

word = raw_input("Enter sequence: ")
a = word.replace('A', 'T')
b = word.replace('C', 'G')
c = word.replace('G', 'C')
d = word.replace('T', 'A')
if a == word and b == word and c == word and d == word:
    print "Reverse complement sequence: ", word

And I want this sort of output:

Enter sequence: CGGTGATGCAAGG
Reverse complement sequence: CCTTGCATCACCG

Regards