Cyanobacteria belong to the oldest organisms of our planet. They use photosynthesis to produce ATP and gain biomass from carbon dioxide. The cyanobacteria Nostoc punctiforme is a filamentous bacterium that consists of two different types of cells, vegetative cells and Heterocysts. The type of cell it differentiates into depends on the media they grow in. In an ammonium-rich medium, the N.punctiforme consists of vegetative cells that differentiate into Heterocysts when in the medium is changed to a low-concentration ammonium medium.