The electron transport chains for photosynthesis is carried out in the thylakoid membranes of chloroplasts. This is mainly due to the availability of chlorophyll molecules and accessory pigments to absorb light energy. These are the must-required ingredients in order to produce ATP molecule while utilizing energy from the sunlight. Chlorophyll molecule acts as a reaction centers and the remaining molecules such as pigments within the membrane form an antenna complex.
Antenna complex, as the name suggests, is responsible for the absorption of light energy (also known as photon molecule) and then, it transfers energy into the reaction centers. These reaction centers are key locations where the photon energy is transferred into the electron transport system.
The electrons enter into an excited state i.e. higher energy state when the reaction center chlorophyll receives light energy. This step is causing them to the outer electron orbitals and then to attach to a protein in the electron transport chain. This is the step when the plant cell transfers light energy to chemical energy.
Electron transport chain is collectively made up of a membrane-embedded proteins and organic molecules. The electronic transport chain components are found in the plasma membrane of prokaryotes, whereas in eukaryotes, many copies of these molecules are found in the inner mitochondrial membrane. The electron transport chain contains proteins such as Fd (ferredoxin), PQ (plastoquinone), Cyt C (cytochrome C), Q (ubiquinone), and PC (plastocyanin). The enzyme NADP reductase is also present. It is important in the reduction of an electron acceptor molecule and in generation of NADPH.
Light-independent reaction is dependent on the products of the light-dependent reaction. However, vice versa is not true. In light-dependent reaction, the absorbed energy is converted into chemical energy in the form of ATP whereas in case of light-independent reaction, glucose molecule is produced by utilizing environmental CO2 and the products of light-dependent reactions- ATP and NADPH. In this, ATP provides energy for glucose synthesis whereas NADPH is required for the reduction of CO2 into glucose.