Non-Cyclic Photophosphorylation / Electron Flow: Pathway 2 Flashcards
How many electrons leave the reaction centre chlorophyll in the cluster of pigments during non-cyclic photophosphorylation?
Two electrons leave the electron acceptor
What happens to the two high-energy electrons when they leave the reaction centre chlorophyll?
They are passed to an electron acceptor and then along a series of electron acceptors
Where do the events of non-cyclic photophosphorylation take place?
The grana of the chloroplast
Why is this electron flow referred to as non-cyclic?
As the energised electrons do not return to the chloroplast
Instead of retuning to the chlorophyll, what happens to the two high-energy electrons?
The two electrons combine with NADP+ to form NADP-
What happens to the electrons as they move form electron acceptor to electron acceptor?
They lose energy which is trapped by ADP and a phosphate and then used to form ATP and water
What do the electrons combine with to form NADP-?
NADP+
What is formed when the two electrons combine with NADP+?
NADP-
What combines with NADP+ to form NADP-?
2e-
To electrons
What happens after NADP- has been formed?
The chlorophyll molecule is now short of electrons so it gains new electrons from the splitting of water - photolysis
Define photolysis.
The splitting of water by light
What is formed from the splitting of 2 water molecules?
3
4H+ (four protons)
4e- (four electrons)
O2 (oxygen gas)
What happens to the protons formed by through photolysis?
They are stored in a proton pool in the chloroplast
What happens to one of the protons stored in the proton pool?
One is attracted to NADP- and combines with it to reduce it to NADPH
Give the chemical formula for the formation of NADP-.
NADP+ +2e- –> NADP-
Give the chemical formula for the formation of NADPH.
NADP- + H+ –> NADPH
What happens when a proton combines with NADP-.
The NADP- is reduced to NADPH
What happens to the electrons formed by photolysis?
Two of the electrons replace the electrons lost by the chlorophyll which restores the number of electrons in the reaction centre chlorophyll
What happens to the oxygen gas formed by photolysis?
2
Some is released out through the stomata into the atmosphere
Some is used internally in the plant in respiration
What is this type of electron flow commonly called?
Non-cyclic electron flow
