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(a) 6 pts. Calculate the ÄG of the H+ gradient across the IMM. Show your work and
WRITE your final answer in the BLANK at LOWER RIGHT. Be careful with UNITS. F o r a n IM M p ro to n g ra d ien t,
Ä G = F (Ä p), w here Ä p = ø (59m V Ä p H ),
ø = V m o f the IM M , a nd Ä pH = (pH cytoplasm /IMS p H m atrix)
H ere, Ä pH = 7 8 = 1
S o Ä p = 1 0 0 m V (59 m V × 1 ) = 1 5 9 m V
Ä G H = F (Ä p ) = 0 .1 kJ/mV m o l × 1 5 9 m V
= 1 5.9 kJ/m ol
F IN A L A N SW ER :__ 15.9 kJ/m ol__
(b ) 2 p ts . W hat is the en ergetically favorable direction o f flow f or H + u n der these
conditions ? IN TO the m atrix
(out o f the cytoplasm /IM S; s ince the Ä G H > 0)
( c) 4 pts. What is the minimum number of protons that will have to flow through the ATP
synthase in order to synthesize one molecule of ATP from ADP and Pi under these
conditions? Answer with an INTEGER. Very briefly, give your reasoning.
num ber F OUR r ea soning 4 m oles H + × 1 5.9 kJ/m ol = 6 4 kJ; just enough to m ake o ne
m ole o f A TP (60 kJ), if the synthase c om plex is 9 4%
efficient -13- NAME: __________KEY________________
MIDTERM EXAM II
19 October 2009
(EC) In honor of Elizabeth Blackburn, Carol Greider, and Jack Szostak recently winning the 2009
Nobel Prize for Medicine for their discovery of and work on telomeras...
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