The plasma membrane isolates the cell but allows interactions with the environment.
Cytoplasm fills each cell and surrounds the nucleus.
The evolution of prokaryotic cells preceded that of eukaryotic cells by 2 billion years. Streptococcus pyogenes , the bacterium that causes strep throat, is an example of a prokaryote. Yeast, the organism that makes bread rise and beer ferment, is an example of an unicellular eukaryote. Humans, of course, are an example of a multicellular eukaryote. 2.They are both membrane bound.