Describe three steps that contribute to the buildup of the proton gradient across the thylakoid membrane.

Three steps that contribute to the buildup of the proton gradient across the thylakoid membrane are 1) the splitting of water inside the membrane by P680+ which increases the concentration of protons in the lumen, 2) the transport of protons into the membrane during electron transport by plastoquinone (PQ) as it moves from photosystem II to the cytochrome complex and back again, and 3) the depletion of protons in the stroma outside the thylakoid by NADP+ reduction.