reet
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http://faculty-staff.ou.edu/B/Robert.A.Berkowitz-...
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| msyamp
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hmm good
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| drk1980
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If a cell is in a steady state,
A) no molecules are moving into or out of the cell
B) the concentration of each type of molecule is the same inside and outside the cell
C) the cell does not use energy
D) all of the above
E) none of the above
plz explain!
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| Natasa
Forum Elite
Topics: 9
Posts: 291
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I think it is D,because you have no net movement of ions,molecules etc and no net use of energy(incoming E=outgoing E of the cell) and the concentration of diffusibile molecules should be the same.
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| drk1980
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At a particular chemical synapse, chloride (Cl-) channels open in the postsynaptic neuron whenever there is an action potential in the presynaptic neuron. In the postsynaptic neuron, the resting membrane potential is –70 mV, the Nernst equilibrium potential for chloride (ECl) is –65 mV, and the action potential threshold is –50 mV. If the postsynaptic neuron is at rest when the presynaptic neuron fires an action potential, the postsynaptic potential (PSP) will
A) be hyperpolarizing
B) be excitatory
C) involve a net influx of Cl-
D) all of the above
E) none of the above
what will it be then?
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| drk1980
Forum Guru
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apparently the answer to the first Q also is "E- none of the above"
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| Natasa
Forum Elite
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Maybe someone could explain this
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| leen
Forum Guru
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pl explain it????
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| jagian75
Forum Newbie
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wanted to clarify here. that in a steady state there would still be a large force acting on the cell because the interior of the cell is around -90mv and the Na is maintained at 45mv. so there will still be some leak of the sodium which is countered by the Na+K+ATPase by potassium influx and sodium efflux and this potassium will be moving out thru the ungated channels. so even at steady state there will besome basic energy used and there will be some movt but it will not produce de/hyperpolarisation but as for the chloride ion its outside and inside is steady at -90mv so there will be no net transfers .
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| jagian75
Forum Newbie
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as for the second if one goes by the Nernst equation . there wont be any influx nor there will be hyperpolarisation or excitation so it will be E
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| giovanni83
Forum Senior
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Posts: 125
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it's E: there are molecules that goes out and in the cell, they are in a dynamic equilibrium: the net result is 0. The concentration of the ion is very different from in and out, it's not true that they are the same: infact K is intracellular and Na estracellular....is it clear now?
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