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Unformatted text preview: les produc ed by PS II reac t with water, releas ing protons in the thy lak oid s pac e.
The ox idation of water by PS II releas es protons in the thy lak oid s pac e.
Elec tron trans port through the PS II c omplex pumps protons ac ros s the thy lak oid membrane. Hin t 2. Where does proton pumping across the thylakoid membrane occur?
The trans port of protons ac ros s the thy lak oid membrane c ontributes to the proton gradient that driv es ATP s y nthes is . This proton trans port is
ac c omplis hed by one of the s mall elec tron c arrier molec ules that s huttles elec trons between the major elec tron trans port c omplex es . As the
c arrier trans ports protons ac ros s the thy lak oid membrane, it als o s huttles elec trons ac ros s the membrane.
Which com ponent of the light reactions is involved in pum ping protons across the thylakoid m em brane?
Pc (plas toc y anin) as it trans fers elec trons from the c y toc hrome c omplex to PS I
Pq (plas toquinone) as it trans fers elec trons from PS II to the c y toc hrome c omplex
the PS I c omplex as it trans fers elec trons from Pc to Fd
Fd (ferredox in) as it trans fers elec trons from PS I to NADP+ reduc tas e
the PS II c omplex as it trans fers elec trons from water to Pq Hin t 3. T he formation of a proton gradient across the thylakoid membrane
When a c hloroplas t is ex pos ed to light, the thy lak oid s pac e bec omes more ac idic (by about 3 pH units ) than it is when the c hloroplas t is in the
dark . This means that the H+ c onc entration is higher in the thy lak oid s pac e than in the s troma.
The proton gradient res ults in part from the elec tron trans port c hain pumping protons ac ros s the membrane agains t their c onc entration gradient.
This protonmotiv e forc e then driv es the s y nthes is of ATP as the protons diffus e bac k ac ros s the membrane through ATP s y nthas e.
ANSWER: se ssion.ma ste r ingbiology.c om/myc t/a ssignme ntPr intVie w? a ssignme ntI D= 2242937 18/41 13- 10- 13 Cha pte r 1...
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This document was uploaded on 02/17/2014 for the course BIOCHEMIST 2550 at Ohio State.
- Spring '14