I've been reading Fasta files a lot recently and I've noticed that these files of DNA sequence are made up of more than just A's, C's, G's, and T's. Because sequencing errors or frequent SNP variants can make it hard to give a clear consensus sequence, each of these other letters represent the ambiguities in the given DNA sequence.
Here's a nice website with a table that shows what all these other letters represent.
And for you frequent FASTA readers that want to memorize the ambiguous DNA code, I've created a Quizlet for just that purpose.
Follow this link to enjoy all the tools on quizlet.com
