Taxonomy/Phylogeny & Life Cycle

Cyanobacteria have been divided into 5 groups, based on their most recent taxonomic grouping completed by Rippka et al (1979). The classification can be found at this source:
http://www-cyanosite.bio.purdue.edu/taxon79.html

Cyanobacteria are part of the domain "bacteria". Cyanobacteria are their own kingdom, phylum and class called, as well, "Cyanobacteria".
[Phylogenetic tree including Cyanobacteria]
Fedor, Karali. (n.d) Tree of Life. Retrieved from:
             http://bioweb.uwlax.edu/bio203/2011/fedor_kara/classification.htm (04/17/2013)


The classification of Cyanobacteria is commonly debated because of their appearance of algae, their ability to photosynthesise, and their lack of a well-defined nucleus with a nuclear membrane. The above tree shows the relationship between bacteria, (where Cyanobacteria falls under Eubacteria) Archaea and Eukarya, which all stem from a common ancestor. The branches indicate that there is a closer relationship with bacteria (where Cyanobacteria has been classified under), and Archaea, than with Cyanobacteria and those under the domain "Eukarya". 

[Life Cycle of Cyanobacteria]

Beckmann, Aike. (n.d) Cyanobacteria Life Cycle. Retrieved  from:
        http://bioweb.uwlax.edu/bio203/2011/fedor_kara/classification.htm (04/17/2013)

Water is a central part of Cyanobacteria's life cycle, as well as sunlight so that they are able to survive, and photosynthesize. Above is a picture of the general life cycle of Cyanobacterium, which includes the splitting of chain-cells, and as mentioned, the process of photosynthesis. Light provides the cell with the ability to begin the process of photosynthesis, Cyanobacteria germinates, gas vesicles form, filaments grow, nitrogen fixation occurs, oxygen is released and the process repeats itself.