Prokaryotic cells are the oldest type of cell, which have been around for approximately 3.5 billion years. They are the first cells on Earth and the first bacteria cells to be found. There are two different kinds of prokaryotic cells Archaea and bacteria. Archaea are ancient microorganisms that play a part in various ecosystems even our own. They also help with nutrient cycling, and carbon fixation, and help produce methane which we use as a natural gas. Archaea can only be found in extreme environments. Prokaryotic cells or primitive cells are simple organic compounds that are surrounded by RNA with a membrane,  these cells have been around for 3.8 million years ago, and some lived in shallow waters and hydrothermal vents. Hydrothermal vents are places where there are volcanic activities and the water heats up.

Eukaryotic cells are the second-oldest cells, they evolved from the prokaryotic cells and originated in endosymbiotic events. Endosymbiotic events are when organisms have other organisms living inside of them. These events often lead to discoveries and new cells. There are four types of eukaryotic cells, protozoans, algae, fungi, plants and animals. Protozoans are single-celled organisms that live worldwide in almost every habitat, they can cause diseases like malaria, amoebiasis, giardiasis, toxoplasmosis, trichomoniasis, and leishmaniasis. Algae are plant-like organisms that are usually aquatic and use photosynthesis to produce energy. Plants and animals are living organisms worldwide. Lastly, fungi are microorganisms that include yeast, moulds and some mushrooms.