Cyclic photophosphorylation

The same electrons are recycled back into PSI via a electron carrier, making a cycle. So the electrons don't go along the rest of the electron transport chain to end up in the stroma which means they aren't available to reduce NADP. The ATP is made in this by the ATP Synthase enzyme that combines ADP and an inorganic phosphate group together.

Reply 2

Alexok

8

What benefits would cyclic phosphorylation have for the plant, or why does it begin to happen

Reply 3

OP

Original post by 123emily

The same electrons are recycled back into PSI via a electron carrier, making a cycle. So the electrons don't go along the rest of the electron transport chain to end up in the stroma which means they aren't available to reduce NADP. The ATP is made in this by the ATP Synthase enzyme that combines ADP and an inorganic phosphate group together.

How do you make ATP with no proton gradient

Reply 4

OP

Original post by Alexok

What benefits would cyclic phosphorylation have for the plant, or why does it begin to happen

when no water is available?

Reply 5

Alexok

8

Original post by The Illuminati

when no water is available?

Oh yeah doh

Reply 6

Original post by The Illuminati

How do you make ATP with no proton gradient

The diagram I have in my revision book shows H+ ions being taken into the stroma by ATP Synthase in the same way as Non-cyclic photophosphorylation (in chemiosmosis to generate ATP) but I'm not sure where the protons come from. :s-smilie:

Are you sure photolysis doesn't occur in cyclic photophosphorylation? I can't think of where else they would come from

Reply 7

OP

Original post by 123emily

The diagram I have in my revision book shows H+ ions being taken into the stroma by ATP Synthase in the same way as Non-cyclic photophosphorylation (in chemiosmosis to generate ATP) but I'm not sure where the protons come from. :s-smilie:

Are you sure photolysis doesn't occur in cyclic photophosphorylation? I can't think of where else they would come from

My textbook and a load of mark schemes say cyclic= no photolysis.
Is your revision book CGP?
????

Reply 8

Original post by The Illuminati

My textbook and a load of mark schemes say cyclic= no photolysis.
Is your revision book CGP?
????

Oh right

Yeah it's CGP

I really don't know where the protons come from then but that's how it shows generation of ATP in cyclic photophosphorylation in the CGP book

Reply 9

OP

Original post by 123emily

Oh right

Yeah it's CGP

I really don't know where the protons come from then but that's how it shows generation of ATP in cyclic photophosphorylation in the CGP book

My CGP book shows H+ too.
Oh well let's just hope that there isn't an 8 mark question on that.

Reply 10

Original post by The Illuminati

My CGP book shows H+ too.
Oh well let's just hope that there isn't an 8 mark question on that.

Yeah lol

and I really hope because it's not in the books that we don't need to know it for the exam

Reply 11

Joe1995

Cyclic photophosphorylation occurs when there is no NADP available to act as the final electron acceptor. So the electron from photosystem 1 replaces itself. Hence why only ATP is produced in cyclic photophosphorylation and not Reduced NADP.

Reply 12

shakerlicious