Figure 3
From: Gene duplications in prokaryotes can be associated with environmental adaptation
![Figure 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2F1471-2164-11-588/MediaObjects/12864_2010_9999_Fig3_HTML.jpg)
Distribution of COG categories. The figure shows distribution of paralogs and persistent singletons according to COG categories, as well as the general distribution of the COG database. '-' is used where no COG group could be identified. The different categories are A: RNA processing and modification, B: chromatin structure and dynamics, C: energy production and conversion, D: cell-cycle control and mitosis, E: amino acid metabolism and transport, F: nucleotide metabolism and transport, G: carbohydrate metabolism and transport, H: coenzyme metabolism, I: lipid metabolism, J: translation, K: transcription, L: replication and repair, M: cell wall/membrane/envelope biogenesis, N: cell motility, O: post-translational modification, protein turnover, chaperone functions, P: inorganic ion transport and metabolism, Q: secondary metabolites biosynthesis, transport and catabolism, R: general functional prediction only, S: function unknown, T: signal transduction, U: intracellular trafficking and secretion, V: defence mechanisms, W: extracellular structures, Y: nuclear structure, Z: cytoskeleton. COG classification A, Y, and Z are not used for prokaryotic COGs.