Signalling Pathways (Solution)

by Adam Hesterberg, Anders Kaseorg, and Chelsea Voss

Convert the three-letter A/C/T/G codes of the original DNA sequence to one-letter protein codes using the standard DNA codon table to get protein1.txt. This file contains a short silly poem, followed by numerous encoded proteins separated by Stop codons. (Note that TAG is used as Pyrrolysine, O, for the poem, but doesn't appear later in the sequence.)

For each protein, convert the amino acid one-letter codes to semaphore. Starting at a point, follow the path formed by the semaphore hands---if one semaphore letter has an up, the next will have a down (to come from) and something else, say a right; the next will then have a left (to come from) and something else, and so on. Each protein forms a complete closed loop. The shapes formed by each protein are in sema1.txt.

These loops are a sequence of drawings of the letters A, C, T, G. Read them off to get dna2.txt, a second DNA sequence.

Now repeat the whole thing on the second DNA sequence to get the protein sequence protein2.txt. The final shapes (sema2.txt) are drawings of the letters F, A, T, so the answer is FAT.