When an electrode is stuck into an intact giant axon

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Unformatted text preview: kJ/mol) = 4.2 = 4 8. (15%) The squid giant axon occupies a unique position in the history of our understanding of cell membrane potentials and nerve action. When an electrode is stuck into an intact giant axon, the membrane potential registers -70 mV. When the axon, suspended in a bath of seawater, is stimulated to conduct a nerve impulse, the membrane potential changes transiently from -70 mV to +40 mV. At 20 ºC, calculate the potential across the resting membrane (a) assuming that it is due solely to K+ and (2) assuming that it is due solely to Na+ . The Na+ and K+ concentrations in axon cytoplasm and in seawater are given in the table. Which calculation is closer to the measured? K+ = +1(293.15K x 8.315 J/mol.K)/96,480 J/ V.mol x ln([9 mM]/[344 mM]) = +0.092 V Figure 1: Table of cation concentration Na+ = +1(293.15K x 8.315 J/mol.K)/96,480 J/ V.mol x ln([430 mM]/[65 mM]) = -.047 V 9. EXTRA Problem. At the mitochondrial respiratory chain, complex I reduce ubiquinol with electrons from NADH. If we block the complex III, ubiquinol is accumulated. At these conditions, it is possible a reverse flow of electrons from ubiquinol to NAD+. What will be the relationship Q between ubiquinol and NAD+ when reverse flow is produced? is it possible to reverse the flow. The relationship between ubiquinol and NAD+ will be +.320 when r eversed 3 4...
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This document was uploaded on 03/06/2014.

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