[sciurus]

I expect that most universities have a core curriculum that requires CS majors to take other science courses. Make those courses genetics and biochemistry and a CS undergraduate can probably get into a 2-year masters program for bioinformatics.

[riprock]

I might get some backlash for this, but while you can apply for some bioinformatics jobs with a MS, PhD is the norm not the exception for biology-related fields. Without a PhD, you won't get very far career-wise.