The cyano bacterial cell possesses a gelatinous sheath of varying thickness and with a cell wall made up of peptidoglycan. The cyano bacterial cell does not have organized nucleus and membrane bound structures such as the Golgi bodies, endoplasmic reticulum and mitochondria. The naked DNA is the genetic material that is dispersed in the central region of the cytoplasm. Lamellae or thylakoids are the flattened vesicular photosynthetic apparatus present. They possess the photosynthetic pigments which are present freely in the cytoplasm. Chlorophyll a is the principal photosynthetic pigment present in addition to it also contains additional pigments like the phycocyanin and the phycoerythrine which gives them the characteristic blue green colour. Certain bacteria have the capacity to change their colour in relation to the wave length of the incident light. This change in the colour is referred to as the Gaidukov phenomenon or complementary chromatic adaptation. Reserve food materials occur as a fat droplets and protein crystals.
