Causative organism of cholera is a bacterium Vibrio cholerae. It is a prokaryote. The causative organism of malaria is Plasmodium which is a protozoan. It is a eukaryote. Ribosomes are the granular structures composed of RNA and proteins. They are not surrounded by any membrane and are seen as dense particles under the electron microscope. Ribosomes found in cytoplasm of eukaryotic organisms are 80S and those in cytoplasm of prokaryotic organisms are 70S, where S is the coefficient of sedimentation and is a measure of the density and size of the ribosome. Mitochondria of eukaryotes also have ribosome which resemble prokaryotes. They are 70S.