Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    7
    ReputationRep:
    Where does the energy to pump protons across the membrane into the thylakoid come from? The textbook i am using is confusing me
    it says in the diagram ''using energy from electrons from chlorophyll'
    but it says ''the energy to drive the process comes from electrons released when water molecules are split by light - photolysis'' in the actual text
    but then it says later that the electrons from water are returned to the chlorophyll molecule. ?


    so if someone can please tell me where the energy to pump protons comes from.. i would highly appreciate it.
    Offline

    19
    ReputationRep:
    (Original post by tmifan)
    Where does the energy to pump protons across the membrane into the thylakoid come from? The textbook i am using is confusing me
    it says in the diagram ''using energy from electrons from chlorophyll'
    but it says ''the energy to drive the process comes from electrons released when water molecules are split by light - photolysis'' in the actual text
    but then it says later that the electrons from water are returned to the chlorophyll molecule. ?


    so if someone can please tell me where the energy to pump protons comes from.. i would highly appreciate it.
    They are all right. When photons of light hit photosystems in Chlorophyll, it excites electrons and these high energy electrons are ejected and travels through series of electron transport chains; in which creates a proton gradient across the thylakoid membrane. Photolysis occurs to replace the lost electrons in the photosystems (inside chlorophyll).

    There are two photosystem you should know: photosystem I (which cyclic photophosphorylation occur) and photosystem II (non-cyclic, which produces the proton gradient for the creation of NADP). During cynic photophoshorylation, the electrons ejected from PSI travels through different electron transport chain, and eventually returns back to PSI. As they travel through electron transport chains, energy is released in which is used to make ATP. In non-cyclic photophosphorylation the electrons do not return back to PSI, and travel all the way to PSII (energy released is used to make ATP) which is then energised and then ejected. This is used to drive the formation of reducing power in the form of NADPH.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Are unpaid trial work shifts fair?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.