Light Reactions FlashCards

Energy into the Photosystem II

Chlorophyll 680 molecule in photo system II absorbs light. Then, it uses its energy from the light and transfers it to the centre. In the centre the electron is excited

Energy Passing

The electron is passed to an electron acceptor

Water Splitting

The water is split and these electrons are supplied one by one in PSII to replace lost electrons

Electron Transport Chains

Each excited electron passes through the electron transport chain. During this phase the electron falls from its excited state by pumping hydrogen positive ions across the cell membrane

Photosystem I

Meanwhile, light energy excites an electron of chlorophyll 700. An electron acceptor captures the electron and transfers the excited electron. The electron is replaced by the ground state electron from the electron transport chain.

NADPH formations

Excited electrons are passed onto NADP+ and Hydrogen positive (using two negative electrons ). A reduction reaction occurs and NADPH is formed

ATP (adenosine triphosphate) synthesis

The concentration of Hydrogen positive ions has now been built up inside the thylakoid membrane. Now as the H+ ions move across the membrane they pass through ATP synthase.


The pumping of the ions is enough energy to attach ADP+P into ATP. #phosphorylation

Electron and energy Movement

Finally the ATP and NADPH move from the thylakoid membranes to the storms where they will play a crucial role in the Calvin cycle!

Light reactions summarized

Takes in: sunlight, water(h2o), ADP+P and NADP+

Results in: Oxygen(o2), ATP and NADPH