Cyanobacteria are the largest and adverse group of photosynthetic bacteria.They were previously known as Blue Green Algae.
They have following characteristics :
Cell Type : They are true Prokaryotes.They lack true nucleus and nuclear membrane.
Size and Shape : They vary greatly in size and shape.Their diameter is range from 1 to 10 um.
Vegetative Structure : They may be unicellular or form colonies of different shapes or form filaments.Filaments are composed of trichomes.Trichome is a chain of cells.Filaments are surrounded by mucilaginous sheath.
Locomation : They lack flagella.They use gas vesicle to move in water.Filamentous species show gliding movements.
Cell wall : They have gram negative type cell wall.
Photosynthetic System : Their photosynthetic system closely resembled to the eukaryotes.They have chlorophyll and photosystem II .They use water as electron donor.They release oxygen during their photosynthesis.Therefore, they carry oxygenic photosynthesis.They use phycobilins as accessory pigments.Photosynthetic pigments and electron transport chain components are located within thylakoids.These pigments are linked to particles phycobilisomes.A blue phycocynin is predominent pigment.
Cyanobacteria fix CO2 through calvin cycle.
Reserve Food material : Their reserve food material is glycogen.
Reproduction : They reproduce asexually by following methods :
They have following characteristics :
Cell Type : They are true Prokaryotes.They lack true nucleus and nuclear membrane.
Size and Shape : They vary greatly in size and shape.Their diameter is range from 1 to 10 um.
Vegetative Structure : They may be unicellular or form colonies of different shapes or form filaments.Filaments are composed of trichomes.Trichome is a chain of cells.Filaments are surrounded by mucilaginous sheath.
Locomation : They lack flagella.They use gas vesicle to move in water.Filamentous species show gliding movements.
Cell wall : They have gram negative type cell wall.
Photosynthetic System : Their photosynthetic system closely resembled to the eukaryotes.They have chlorophyll and photosystem II .They use water as electron donor.They release oxygen during their photosynthesis.Therefore, they carry oxygenic photosynthesis.They use phycobilins as accessory pigments.Photosynthetic pigments and electron transport chain components are located within thylakoids.These pigments are linked to particles phycobilisomes.A blue phycocynin is predominent pigment.
Cyanobacteria fix CO2 through calvin cycle.
Reserve Food material : Their reserve food material is glycogen.
Reproduction : They reproduce asexually by following methods :
- Binary fission : Cell simply divides into two.
- Fragmentation : The filament of cyanobacteria breaks to form special cells called heterocysts.The broken pieces of filament are called hormogonia.Hormogonia grow to form new filaments.
- Akinetes : Akinetes are thick walled,enlarge reproductive cell.These are special reproductive cells.
Structure of Cyanobacterium
Reviewed by M.Zulqarnain
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Reviewed by M.Zulqarnain
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