light dependent reaction(photosynthesis)

light reaction

occurs in the thylakoid

light reaction function

converts solar energy into chemical energy

ATP and NADPH

energy molecules produced for use in the Calvin cycle

chlorophyll a

pigment that begins the light reaction when it absorbs light

photosystems

structures containing pigments and proteins that capture light

reaction center

protein complex with chlorophyll a and a primary electron acceptor

light-harvesting complexes

pigments bound to proteins that capture and transfer light energy

photosystem II

first photosystem with reaction center P680

P680

chlorophyll a that absorbs light at 680 nm

photosystem I

photosystem with reaction center P700

chlorophyll a

absorbs light at 700 nm

pigment excitation

light energy absorbed and transferred until reaching chlorophyll a

excited electron

energized electron passed to the primary electron acceptor

P680

P680 is a strong oxidizing agent that pulls electrons

photolysis

splitting of water to replace electrons lost by P680

electron transport chain

protein chain moving electrons from PSII to PSI

electron energy loss

electrons lose energy as they travel along the ETC

hydrogen ion pumping

ETC energy pumps H+ into thylakoid lumen

electrochemical gradient

buildup of H+ inside thylakoid lumen

proton

another name for H+

PSI electron arrival

electrons from PSII arrive at PSI

PSI excitation

electrons in PSI are re-excited by light

NADPH formation

PSI electrons are used to make NADPH

chemiosmosis

H+ flows through ATP synthase to produce ATP

ATP synthase

enzyme that generates ATP using H+ gradient

noncyclic electron flow

electrons move from PSII → PSI producing ATP and NADPH

cyclic electron flow

PSI electrons cycle back to the ETC to make extra ATP

calvin cycle ATP need

the Calvin cycle requires more ATP than NADPH