All cells, whether prokaryotic or eukaryotic, have these cellular components in common: 

1. DNA, which is the genetic material of the cell
2. Cell membrane or plasma membrane, which is the outermost covering that envelopes the cell completely, shielding the interior components of the cell from the surrounding environment
3. Cytoplasm, a jelly-like aqueous region within the cell in which other cellular components and organelles lie embedded 
4. Ribosomes, which play an integral role in protein synthesis