Chlorophylles

Chlorophylles are a family of light-absorbing pigments that play a central role in photosynthesis in plants, algae, and many cyanobacteria. They capture light energy and funnel excitation to chlorophyll a in the photosynthetic reaction centers, where it drives the chemical reactions that convert light into chemical energy and reducing power.

Most chlorophylles share a common chemical framework: a porphyrin-like ring with a central magnesium ion and a long hydrophobic phytol side chain that anchors the molecule in the thylakoid membranes of chloroplasts or related organelles. This structure enables efficient light absorption and energy transfer within pigment–protein complexes.

The best known forms are chlorophyll a and chlorophyll b. Chlorophyll a is the primary pigment involved directly in charge separation during photosynthesis, while chlorophyll b acts as an accessory pigment that broadens the range of usable light and passes energy to chlorophyll a. Other chlorophylls occur in specific groups of algae and bacteria, including chlorophyll c, d, e, and f, each associated with particular light environments and ecological niches.

Chlorophylls absorb mainly in the blue and red regions of the spectrum, with accessory pigments extending the range of usable light. In photosynthetic complexes, chlorophylls are organized into light-harvesting antennas and reaction centers, enabling efficient transfer of energy and electrons necessary for carbon fixation. The biosynthesis of chlorophylles occurs in plastids and is tightly coordinated with overall cell metabolism and development.