Question

Calculate the Nernst Potential generated across a cell membrane that is selectively permeable to K+. Temperature 27 deg C. K+ out = 62 mM. K+ in = 243 mM. Your answer must be expressed in mV (to the nearest mV) and you must include the units.

Answer #1

Use the Nernst equation to calculate the membrane potential (in
mV) for Ca(2+) if the concentration of Ca(2+) inside the cell is
5mM and outside the concentration of Ca(2+) is 140mM. You should do
this calculation at body temperature, 37C (310K).

A cell’s membrane is permeable to K+, Na+,
and Cl─. Use the following information
to determine
the equilibrium potential of this cell. Assume
that the cell is at 37º C.
K+
Na+
Cl─
Permeability (m/s)
100
1
1000
Outside Concentration (mM)
4.5
145
116
Inside Concentration (mM)
150
12
4.2
[mM = 0.001 Moles / liter.]
70.0 mV
-14.3 mV
-60.5 mV
-88.3 mV

In a two-compartment model of a cell with a K+- and
Na+-permeable membrane and a 10-fold excess of K+ in the inside
compartment, how would the membrane potential change if all K+ ions
were replaced by Na+ ions?
a. It would double.
b. It would be reduced by half.
c. It would not change.
d. It would become positive.
e. No potential would be generated.

Ions A and B in the Table below are both monovalent cations
associated with a cell with a membrane potential of
-98 mV. Constants you may need to answer the questions
associated with the Table are as follows: R = 0.002 kcal/mol
o; T =
310o; F = 0.023 kcal/mol mV
Ion
ICF (mM)
ECF (mM)
A
14.5
96.8
B
105.6
3.2
What is Ion A’s equilibrium potential? (round to nearest whole
number and give units)
2. What is the...

Ions A and B in the Table below are both monovalent cations
associated with a cell with a membrane potential of -98 mV.
Constants you may need to answer the questions associated with the
Table are as follows: R = 0.002 kcal/mol
o; T =
310o; F = 0.023 kcal/mol mV
Ion
ICF (mM)
ECF (mM)
A
14.5
96.8
B
105.6
3.2
What is Ion A’s equilibrium potential? (round to nearest whole
number and give units) _______________________________
What is the...

A typical cell has a membrane potential of -70 mV, meaning that
the potential inside the cell is 70 mV less than the potential
outside due to a layer of negative charge on the inner surface of
the cell wall and a layer of positive charge on the outer surface.
This effectively makes the cell wall a charged capacitor. Because a
cell's diameter is much larger than the wall thickness, it is
reasonable to ignore the curvature of the cell...

The Table lists initial solute concentrations across a 100 MWCO
dialysis membrane. Answer the questions below the table for the
condition that would occur when the system reaches equilibrium.
Constants you will need are as follows:
R=0.082 L atm/mol K; T=310 K
Solution A
Solution B
2.0 mM CaCl2
4.0 mM Albumin
2.5 mM Glucose
4.0 mM Glucose
3.0 mM NaCl
2.0 mM Urea
1.5 mM Albumin
3.0 mM Urea
What is the osmotic pressure (in mmHg) exerted by Solution...

The net charge difference across the membrane, just like the
charge difference across the plates of a capacitor, is what leads
to the voltage across the membrane.
How much excess charge (in picocoulombs, where 1 pc =
1x10-12 C) must lie on either side of the membrane of an
axon of length 2 cm to provide this potential difference (0.07 V)
across the membrane? You may consider that a net positive charge
with this value lies just outside the axon...

Diffusion of gases across a permeable
membrane
1. How long did it take the O2 levels to become about equal
outside and inside the cell? What happened to those levels after
they became about equal over the additional 10 seconds? Why did
this happen?
My answer: It took 6 seconds to become equal. After they became
about equal over the additional 10 seconds they fluctuate back and
forth as equal equilibrium is achieved.
2.Cell use O2 and produce CO2 as...

± Cell Potential and Free Energy Free-energy change, ΔG∘, is
related to cell potential, E∘, by the equation ΔG∘=−nFE∘ where n is
the number of moles of electrons transferred and F=96,500C/(mol e−)
is the Faraday constant. When E∘ is measured in volts, ΔG∘ must be
in joules since 1 J=1 C⋅V.
Part A Calculate the standard free-energy change at 25 ∘C for
the following reaction:
Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)
Express your answer to three significant figures and include the
appropriate units.
Part B...

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