Prokaryotic cells have four main components: 

• Plasma membrane – This is the outer protective covering that separates the interior of the cell from its external environment. The plasma membrane is made up of phospholipid molecules. 
• Cytoplasm – This is the jelly-like substance inside the cell, which is enclosed by the plasma membrane. All the cell organelles are suspended in the cytoplasm. 
• DNA – This is the genetic material of the cell. The DNA in prokaryotes is circular. 
• Ribosomes – Protein synthesis occurs in these molecules.