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Cyanobacteria, also known as blue-green algae, are the oldest known prokaryotes, single-celled organisms, obtaining their energy through photosynthesis.1 These life forms can manufacture the carbon they use for processes within the cell from the carbon dioxide in the atmosphere. At the same time, they are able to fix nitrogen gas in molecular form. The fact that these processes take place in the same place requires careful reflection and totally refutes the evolutionists idea that these life forms are “primitive.”
The enzyme nitrogenase, which is responsible for nitrogen fixation, is exceedingly sensitive to oxygen. For that reason, nitrogen fixation and the process of photosynthesis, which requires oxygen, should not be able to take place at the same time in cyanobacteria cells. In order to overcome this difficulty, the filaments in some cyanobacteria restrict the nitrogen fixation process with a special kind of cell known as heterocysts.
With their unique structure, heterocyst cells enable these two incompatible processes to be performed by the cyanobacteria.
In order to restrict the entry of oxygen, heterocyst cells are covered with a special sheath containing glycolipid and polysaccharide, a protective homogeneous envelope. A layer four nanometers thick develops through the interaction of waterproof chains, and this restricts the permeability of dissolved substances. Heterocysts have four separate membranes consisting of double-layer lipids, and these have different structures and functions.
In this way, carbon dioxide fixing through photosynthesis and nitrogen fixation in an oxygen-free environment, which cannot happen at the same time, are separated from one another, and cyanobacteria are able to discharge their functions.