What does the highligted part mean?
Does it mean Energy is required to pump H+ into the lumen?
If it is true, then why does this happen at all, lose energy(in pumping H+ into the lumen) to produce energy (through Chemiosmosis)? Isn't it wasteful?
Dear student,
Energy is required to pump H+ into the lumen
the pigments and electron acceptors of the light - dependent reactions are embedded in the thylakoid membrane. Energy released from the circulation of the chain of acceptors used to purpm protons from the strorma, across the thylakoid membrane, and in the thylakoid lumen. Thus, the pumping of protons results in the formation of a proton Gradient of the thylakoid membrane, Protons also accumulate in the thylakoid lumen as water is split during noncyclic electron transport. Because protons are actually hydrogen ions (H+), the accumulation of protons causes the pH of about 5 in the thylakoid lumen, compared to a pH of about 8 in the stroma, 'This difference of about 3 pH units across the thylalkoid membrane means there is an almost thousand-fold difference in hydrogen ion concentration.
The proton gradient has a great deal of free energy How does the chloroplast convert it into a more useful form? According to the general principles of diffusion, the concentrated protons inside the thylakoid may be expected to diffuse out easily. However, they are prevented from doing so because the thylakoid membrane is impermable to H+
Energy is required to pump H+ into the lumen
the pigments and electron acceptors of the light - dependent reactions are embedded in the thylakoid membrane. Energy released from the circulation of the chain of acceptors used to purpm protons from the strorma, across the thylakoid membrane, and in the thylakoid lumen. Thus, the pumping of protons results in the formation of a proton Gradient of the thylakoid membrane, Protons also accumulate in the thylakoid lumen as water is split during noncyclic electron transport. Because protons are actually hydrogen ions (H+), the accumulation of protons causes the pH of about 5 in the thylakoid lumen, compared to a pH of about 8 in the stroma, 'This difference of about 3 pH units across the thylalkoid membrane means there is an almost thousand-fold difference in hydrogen ion concentration.
The proton gradient has a great deal of free energy How does the chloroplast convert it into a more useful form? According to the general principles of diffusion, the concentrated protons inside the thylakoid may be expected to diffuse out easily. However, they are prevented from doing so because the thylakoid membrane is impermable to H+
- It does not happen through chemosis and it is not wasteful