1. Photosynthesis a) What are the sources of protons that contribute to the gene
ID: 135313 • Letter: 1
Question
1. Photosynthesis
a) What are the sources of protons that contribute to the generation of a proton gradient in chloroplasts? Protons removed from the stroma by the reduction of NADP+
b) You have invented a new herbicide that inhibits the CF1-CF0 ATP synthase in chloroplasts by uncoupling proton transport from ATP synthesis. (This means that when treated with
herbicide, protons pass through ATP synthase but no ATP is generated.) How would this herbicide affect the functioning of the light reactions?
c) What is the MOST LIKELY effect on the light reactions if ferrodoxin - NADP+ reductase activity is inhibited?
Explanation / Answer
1.a.
Oxidation of water: protons are released during photolysis of water.
Stroma: H+ is pumped into the lumen by cytrochrome bf complex.
Reduction of NADPH: when NADP+is not available to accept electron from reduced ferredoxin, H+ can be obtained from NADPH.
1.b.
No effect on light reactions except ATP would not be forming.
1.c.
Electron transfer from photosystem I to NADP+ will cease. As a result, NADPH formation will diminish.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.