The Antenna Complex

The reaction center of a photosystem alone is not efficient enough to meet the energy demand of the electron transport chain.

So, it is assisted by a surrounding antenna or light-harvesting complex, which comprises several hundred pigment molecules, including chlorophyll a, b, and other accessory pigments.

Unlike the reaction center, the photochemically inactive antenna complex pigments cannot directly convert light energy into chemical energy.

However, these pigments absorb photons of varying wavelengths and rapidly transfer energy to the adjacent pigments.

These antenna pigments are positioned close to each other by a protein scaffold, forming an energy-efficient complex.

As a result, the energy absorbed by the antenna complex is channeled through a network of pigment molecules to the reaction center.

Finally, a special pair of chlorophyll molecules in the reaction center absorbs these photons.

The reaction center can now transmit an adequate number of electrons to the electron transport chain, enhancing its yield.