How is the ATP made during light reactions?

Question

I honestly cant find anything in my biology book that explains it...help

Answer 1

LIGHT REACTION:

light reaction takes place in the thylakoid membranes of the chloroplast.the thylakoid membranes contain special types of chlorophyll molecules P 680 and P 700 forming photosystem I and photosystem II.light is absorbed in these two photosystems.when light is absorbed,the chlorophyll molecule gets excited and gives off electrons.the electrons are passed through various electron acceptors.during this transfer a lot of energy is released.this energy is used to synthesize energy rich molucules like ATP(adenosine triphosphate)and NADPH²(reduced nicotinamide adenine dinucleotide hydrogen phosphate).the flow of electrons also results in splitting of water(called photolysis of water)and during this,oxygen is given out from water.since this whole reaction was discovered by Hill,it is called as Hill reaction.

Answer 2

Hydrogen ions, H+, build up inside the thylakoids in two ways:

H+ from water molecules accumulate when the water is split and the electrons are given to the chlorophyll in Photosystem II and the oxygen is released.

H+ from outside the thylakoids are pumped into the thylakoid space using energy from the electron transport chain that occurs between Photosystem II and Photosystem I.

At any rate, the H+ build up inside the thylakoid space until they rush out through a spinnable protein that is part of the thylakoid membrane. The flow of H+ through that protein (I tell my students it's the ATP-maker protein) provides energy to fasten phosphates to ADPs making ATP.

Once the H+ are outside the thylakoid, some of them attach to NADP+ with some high energy electrons and are transported to the Calvin cycle. Other H+ just get pumped back into the thylakoid space and rush out through the ATP-maker again. Six Flags for H+!!!!

Answer 3

Electrons excited out of the reaction centre contained in the photosystems are carried alongside a set. The chain pumps protons, clone of the respiration complexes, and the electrons are finally dumped onto NADP to type NADPH. Protons flow decrease back by ability of ATP synthase, generating ATP.