They are not a valid example of how a cell can function without DNA. Their only function is to float around and have stuff stuck to them. Other cells actually have to produce proteins and such.
At least, that's how I think it works. Are there any cells (other than red blood cells) that can actually "function" (do things, not just have things done to them) without DNA?
All cells don't need their DNAs until it is time to reproduce or repair, unless there is a kind of cell in perpetual growth like cancer cells or stem cells. The nucleus of the cell is not the 'brain' but the nads. Our football team was named the Nads. Our cheer was Go! Nads!The brain function is in the cell membranes.