<P> Respiration in cyanobacteria can occur in the thylakoid membrane alongside photosynthesis, with their photosynthetic electron transport sharing the same compartment as the components of respiratory electron transport . While the goal of photosynthesis is to store energy by building carbohydrates from CO, respiration is the reverse of this, with carbohydrates turned back into CO accompanying energy release . </P> <P> Cyanobacteria appear to separate these two processes with their plasma membrane containing only components of the respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electron transport chain . Cyanobacteria use electrons from succinate dehydrogenase rather than from NADPH for respiration . </P> <P> Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success . The water - oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z - scheme). In contrast to green sulfur bacteria which only use one photosystem, the use of water as an electron donor is energetically demanding, requiring two photosystems . </P> <P> Attached to the thylakoid membrane, phycobilisomes act as light - harvesting antennae for the photosystems . The phycobilisome components (phycobiliproteins) are responsible for the blue - green pigmentation of most cyanobacteria . The variations on this theme are due mainly to carotenoids and phycoerythrins that give the cells their red - brownish coloration . In some cyanobacteria, the color of light influences the composition of phycobilisomes . In green light, the cells accumulate more phycoerythrin, whereas in red light they produce more phycocyanin . Thus, the bacteria appear green in red light and red in green light . This process of complementary chromatic adaptation is a way for the cells to maximize the use of available light for photosynthesis . </P>

Cell wall material present only in bacteria and blue green algae