How did the development of CRISPR-Cas9 first occur? How do you know? A Charpentier worked with Doudna at the University of California. "Doudna is a professor at the University of California, Berkeley. This is the first science Nobel Prize to be awarded to an all-female team." B Charpentier was studying bacteria. "She discovered a molecule called tracrRNA. It is a part of the bacteria's system of immune defense known as CRISPR-Cas. Like humans, viruses attack bacteria, too." C Charpentier was studying viruses. "The viral code is sandwiched between repeating sections of the bacteria's own DNA. Together, the line of DNA is known as CRISPR." D Charpentier worked with Doudna to slice proteins. "The Cas9 from CRISPR-Cas9 is just one of many different slicing proteins. One part of CRISPR targets DNA while the Cas proteins do the cutting."