9: To be or not to be… in blast

To be or not to be … in blast

Back to Bess — who still believes that all the possible 165-nucleotide sequences have already been discovered and catalogued in BLAST. After all, she reasons, the BLAST human genome contains about 5 trillion sequences, which does seem like an awful lot.

Recall, however, that we found that 2.19 × 10⁹⁹ 165-nucleotide sequences are theoretically possible. What percentage of the theoretically possible sequences are actually contained in BLAST?

In other words, if you wanted to write this as a percentage, you would need more than 80 zeros after the decimal
point, like this:

0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000023%