Photosynthesis Z Scheme Electron Flow — a labelled NEET Biology diagram with a definitions lexicon.
Photosynthesis Z-Scheme Electron Flow Labelled parts: Photosynthesis Z-scheme (light reactions), Photosystem II (PSII), Photosystem I (PSI), Light, Water splitting, O2, Plastoquinone (PQ), Cytochrome b6f complex, Plastocyanin (PC), Ferredoxin (Fd), NADP+ reductase, NADPH, ATP, ADP + Pi, Stroma, Electron flow, Proton movement, Linear electron flow, Cyclic electron flow, Chemiosmosis. A mobile electron carrier molecule in the thylakoid membrane of chloroplasts, involved in the electron transport chain during the light-dependent reactions of photosynthesis. FYI: Plastoquinone accepts electrons from Photosystem II (PSII) and transfers them to the Cytochrome b6f complex. A protein complex located in the thylakoid membrane that accepts electrons from plastoquinone and passes them to plastocyanin, contributing to the proton gradient. FYI: This complex is crucial for the pumping of protons (H+) from the stroma into the thylakoid lumen, establishing the proton motive force. It is a small, copper-containing protein that acts as an electron carrier in the thylakoid membrane of chloroplasts. It transfers electrons from the cytochrome complex to Photosystem I (PSI). FYI: Plastocyanin's role is crucial for the transfer of electrons between the cytochrome complex and PSI, maintaining the linear electron flow. This is a small protein containing iron-sulfur clusters that accepts electrons from Photosystem I (PSI). It subsequently transfers these electrons to various electron acceptors, including NADP+ reductase. FYI: Ferredoxin is the terminal electron carrier in the linear electron flow pathway, passing electrons to NADP+ reductase. This enzyme catalyzes the final step of the light-dependent reactions, reducing NADP+ to NADPH using electrons received from ferredoxin. This reaction is essential for providing reducing power for the Calvin cycle. FYI: The reduction of NADP+ to NADPH by NADP+ reductase occurs in the stroma and is vital for the fixation of CO2 in the Calvin cycle. This process describes the movement of electrons from water, through Photosystem II (PSII) and Photosystem I (PSI), ultimately leading to the formation of NADPH and ATP. It is the primary mechanism for generating energy in photosynthesis. FYI: Linear electron flow involves both PSII and PSI and is responsible for the splitting of water (photolysis) and the generation of both ATP and NADPH. In this process, electrons pass from Photosystem I (PSI) back to the cytochrome complex, bypassing PSII. This cycle does not produce NADPH but significantly increases the proton gradient across the thylakoid membrane. FYI: Cyclic electron flow is primarily used to generate extra ATP when the cell needs more energy (ATP) relative to reducing power (NADPH). Also known as photolysis, this process occurs at Photosystem II (PSII) where water molecules are oxidized to release electrons (e⁻), protons (H⁺), and molecular oxygen (O₂). The electrons replace those lost by PSII. FYI: The splitting of water (2H₂O → 4H⁺ + O₂ + 4e⁻) is the source of electrons for the entire photosynthetic process and releases oxygen as a byproduct.