Evolutionary role of Cyanobacteria

Cyanobacteria are a group of bacteria .they are photosynthetic .they are aquatic and are also found in moist soils. they have bluish green colouration. they are also called blue green algae because they arep photosynthetic and aquatic like algae.actually they are not algae but bacteria.algae are eukaryotes but cyanobacteria are prokaryotes.evolutionary they are very important group of organisms .their fossils have been traced back to 3.5bilion years ago . during evolutionary history of Earth they played important role by converting the reducing environment of Earth to oxidizing.they added oxygen to the earth environment by their photosynthetic activity.this paved the way for origin of aerobic organisms.they also played important role in origin of plants .according to endosymbiotic theory somewhere in proterozoic or Cambrian era a cyanobacteria entered a eukaryotic cell.here it found shelter and by photosynthetic activity provided food and oxygen to host cell also.gradualy this cyanobacteria got modified into chloroplast.
By : Ashwani,biology teacher,Phagwara.