usmleasr
Forum Guru
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Posts: 970
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1. ΔG0'
V ↔ W –4.0
W ↔ X +0.4
X ↔ Y –3.4
Y ↔ Z +5.7
From the values of ΔG0' given in the table, which compound in the overall metabolic pathway V ↔ W ↔ X ↔ Y ↔ Z will accumulate in the largest amount at equilibrium?
A) V
B) W
C) X
D) Y
E) Z
please explain the ans
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| black_tulip
Forum Senior
Topics: 14
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it is Y.
V <--> Y = -4+0.4-3.4 =-7
so Y collects 7 energy. Is it the largest?
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| Malaysian
Forum Guru
Topics: 28
Posts: 778
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I feel its Y too.....anyone else knows??
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| santaclara
Forum Elite
Topics: 67
Posts: 299
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CAN U PLEASE EXPLAIN THIS Q?
thanx
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| SunnyD
Forum Newbie
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Posts: 4
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Black_tulip pretty much hit on it. Since the reaction Y <-> Z has the highest energy of reaction, Y is going to accumulate in high concentrations until some enzyme comes along and lowers that energy of reaction. So the answer is Y.
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| mash
Forum Fanatic
Topics: 147
Posts: 1,326
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ans is Z
if delta G is -ve ===> spontaneous rxn
V ↔ W –4.0
W ↔ X +0.4
X ↔ Y –3.4
Y ↔ Z +5.7
(-4)+(+0.4)+(-3.4)+(+5.7)= -1.3
if sum of delta Go is -ve then rxn proceeds spontaneously and the product of last rxn accumulates(no matter wat the sign of delta G in last rxn)
(and Z will inhibit 1st rxn i.e. V<--->W in this case)
___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius
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| SunnyD
Forum Newbie
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So is the key to the question the line "at equilibrium"? I'm now wondering if I don't understand it completely. What mash just said makes sense, but I''m now torn between both answers because I'm certain what I said about the energy of the individual reactions is correct. Anyone with some clarity on the way the question is phrased itself?
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| Malaysian
Forum Guru
Topics: 28
Posts: 778
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What Mash says is right that its a spontaneous reaction however since the last enzyme is the 'rate limiting enzyme' it works the slowest leading to a buildup of Y.
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