 All organisms are different. Humans, animals and plants are known as eukaryotes, whilst bacteria and fungi are known as prokaryotes. So what exactly are prokaryotes? They are single celled organisms and are built in a capsule-like shape. These organisms are filled with cytosol, which is known as intracellular fluid. Prokaryotes also have a flagellum, which is a tail-like structure that provides them with agile mobility. Here you can see more detailed structure of the prokaryotic cell. The DNA in prokaryotes is small and circular and floats within the cell cytosol. The genetic material is not enclosed within a nucleus. This is because prokaryotes don't actually have any membrane bound organelles. In addition to the bacterial DNA, prokaryotes also contain genetic material in plasmids. These are small and circular and have the ability to replicate independently. Because of this feature, plasmids are frequently used in research for genetic engineering. It is important to note that they contain less genetic material than eukaryotes. One reason is because genetic material in prokaryotes is not condensed, meaning that there is both less space for the DNA to be stored and less capability for storing it. Similar to some eukaryotes, as prokaryotes cannot sexually reproduce, they use another mechanism to replicate, known as binary fission. Untaken binary fission allows prokaryotic organisms to produce exact duplicate copies of themselves. As the process is not very complex and no genetic variability occurs, these cells replicate extremely quickly. This can be seen in the case of an infection, where once infected, the cells replicate and spread the bacteria throughout the body at a rapid rate. Eukaryotic cells are quite different to prokaryotes, however the first difference is that they can be either unicellular or multicellular. Research has put forward a symbiotic theory between prokaryotes and eukaryotes, based on mitochondria and chloroplasts containing their own DNA. It is thought that as they are genetically independent, these organelles were once prokaryotic beings. It is also important to note that eukaryotic organisms can be further broken down into two sub-tacs. These are animal cells and plant cells. As shown, animal cells have no cell wall, do not contain chloroplasts and have only small vacuoles. Comparatively, plant cells have large vacuoles, a cell wall made from cellulose and chloroplast organelles. Plant cells have chloroplasts to promote photosynthetic processes, given that they can convert light into chemical energy. Here you can see a more detailed structure of both the animal and plant cells. As eukaryotes have membrane-bound organelles, this means that they store their genetic material within the nucleus. Genetic material is extremely condensed into chromosomes. This genetic material stored within the chromosomes is replicated by either mitosis or meiosis. By undertaking meiosis, eukaryote DNA can have greater genetic variability. This is shown when humans reproduce, as genetic material from both parents is exchanged and that offspring contains a mixture of both parents' DNA. So now it's time to put prokaryotes and eukaryotes head-to-head and directly compare them both. This table here provides a succinct summary of the key comparisons we covered between them. And once you know these, you'll be able to distinguish between prokaryotes and eukaryotes with your eyes closed.