Of course, this is true. Simply it is a fact that prokaryotes don't have any nucleus while eukaryotes have well defined nucleus. These difference between prokaryotic and eukaryotic cell discriminate themselves from one another. Bacteria are prokaryote so we may say that eukaryote is descended from bacteria. It is easy to prove too. Look, bacteria is itself a prokaryote so it is an older one unicellular organism. It belongs to lower level of organization this is why it is prokaryote. But it igives rise to net level of organization, that level of organization is also unicellular but is comprised of enveloped nucleus. This shows that those nuclei containing ells are higher level of organization after bacteria. This one is the next step towards development of organization so we may say that bacteria is the descendent of eukaryotic organisms. Hope it is now clear to you, if you still have to search then you have to go for Bacteria details along with some stuff from the organization of organisms. You may study both levels of organizations; i.e. Eukaryote and prokaryote.