Cyanobacterium
Photosynthetic Prokaryote
About the Cyanobacterium
Photosynthetic Prokaryote
Oceans, lakes, soil
Cyanobacteria photosynthesise in nearly every sunlit habitat and helped create the oxygen in our atmosphere.
Clinical and real-world context
Some cyanobacteria make toxins in water blooms, and they show how photosynthesis works without chloroplasts.
3 structures to explore
Thylakoid Membranes
Photosynthesis without chloroplasts
Layers of thylakoid membrane run just inside the cell, holding the pigments that capture light. They are not enclosed in a chloroplast.
Chloroplasts are thought to descend from ancient cyanobacteria taken in by another cell.
Carboxysome
The carbon-fixing compartment
Carboxysomes are protein-shelled compartments that pack the enzyme rubisco together with CO2 so carbon fixation works faster.
Carboxysomes are bacterial compartments built without any lipid membrane.
Nucleoid
The naked genome
Like other bacteria, cyanobacteria keep their DNA in an open region of the cytoplasm with no nuclear envelope.
Some cyanobacteria carry several copies of their chromosome in each cell.