The scientist you're looking for is an anthropologist.
THe answer to this question would be: ribosome.
Ribosome function is in protein synthesis. To do synthesis a protein, it will need an RNA with a specific structure. The RNA is made from the nucleus, so if nucleus can copy their DNA into RNA, the protein synthesis will not be able to be executed.
A = Phosphate group
B = Deoxyribose sugar
C = Nitrogenous base
