Light Reaction Guided Notes

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll.

Light Reaction

Part of photosynthesis that occurs in the thylakoids, converting light energy into chemical energy in the form of ATP and NADPH.

Calvin Cycle

Part of photosynthesis that occurs in the stroma, using ATP and NADPH to convert CO2 into glucose.

Photolysis

The process of using light energy to break down water molecules, producing oxygen, protons, and electrons.

Oxidation

The loss of electrons during a reaction, which increases the oxidation state of a molecule.

Reduction

The gain of electrons during a reaction, which decreases the oxidation state of a molecule.

Chemiosmosis

The movement of ions across a selectively permeable membrane, down their electrochemical gradient, which in this case refers to protons moving through ATP synthase to generate ATP.

ATP Synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate during the process of chemiosmosis.

Photosystem

A complex of proteins and pigments in the thylakoid membrane that captures light energy, initiating the process of photosynthesis.

NADP+/NADPH

NADP+ is the oxidized form (electron-deficient), and NADPH is the reduced form (electron-rich), acting as an electron carrier in photosynthesis.

Proton Gradient

A difference in the concentration of protons (H+) across a membrane, which drives ATP synthesis in photosynthesis.

Non-cyclic Photophosphorylation

A process in photosynthesis where electrons flow from water to PSII to the first ETC, then to PSI and finally to NADP+, leading to the generation of both ATP and NADPH.

Cyclic Photophosphorylation

A process where electrons from PSI return to PSI after passing through the first ETC, resulting in the production of ATP without the generation of NADPH.