Magnesium (Mg²⁺) is the ion that is central to the formation of chlorophyll.
Chlorophyll, the pigment responsible for capturing light energy in plants during photosynthesis, has a structure very similar to heme, the iron-containing molecule in hemoglobin that carries oxygen in red blood cells. The critical difference is that chlorophyll uses a magnesium ion (Mg²⁺) instead of an iron ion in its central structure. This magnesium ion is coordinated within a porphyrin ring, which is a complex organic molecule.
The magnesium ion's presence and its specific coordination within the porphyrin ring are essential for chlorophyll to absorb light effectively and initiate the process of photosynthesis. Without magnesium, the chlorophyll molecule cannot be properly formed, and photosynthesis cannot occur.
In essence, while iron plays a key role in oxygen transport in animals, magnesium serves an analogous role in light energy capture in plants.
