Cells were recognized by Robert Hooke in 1665. One of the main differences between unicellular organisms and multicellular organisms is that unicellular organisms have one cell and are small, and multicellular organisms have more than one cell in them and are large. Unicellular organisms fall under the classification of prokaryotes because their structure isn’t complicated. Considering there is no nucleus in prokaryotes, this leads to their impotence to handle their surface area to volume ratios. Thus, the area a unicellular organism takes up is small-it’s the opposite for multicellular organisms. Multicellular organisms like algae can have a nucleus; which lets them manage their surface area to volume ratio. As the cell gets larger, the surface area to volume ratio gets smaller. Therefore, if the cell grows exceeding a definite perimeter, not enough material will be capable of traversing the membrane swiftly enough to harbor the enlarged cellular volume. When this occurs, the cell must allocate into smaller cells with the favorable surface area to volume ratios, or terminate function. The requirements for life in a cell are having a way of storing information (Deoxyribonucleic acid), a way of producing fuel (Adenosine triphosphate synthase), a means of duplicating for reproduction, and a cell membrane. Since a unicellular organism only has one cell, the cell must be able to carry out all these functions. A multicellular organism is large because there needs to be more than one cell in order for the functions to be carried out. The definition of growth is becoming greater in size and multicellular organisms grow by producing cells (this is one of the requirements for life in a cell: reproduction). Prokaryotic cells have creases in the cell membrane which are accountable for roles like respiration. These creases also increase the surface area. Eukaryotic cells are compartmentalized. This is a procedure to expand the surface area because there’s plenty of membranes inside the cell. Additionally, compartmentalization allows eukaryotic cells to execute chemical reactions, gain nutrients and expel waste.