Biology 222
Exam 1, Fall 2009
Name__________________________
Page 1
This exam is doublesided.
Put your first and last name on every sheet!
Every sheet missing your name will lose 1 point.
Answer all questions on pages 312.
E
QUATIONS YOU MAY FIND HELPFUL
At 20
°
C
]
[
]
[
log
58
10
in
out
z
mV
E
x
=
Otherwise,
]
[
]
[
log
303
.
2
10
in
out
zF
RT
E
x
=
where
R
= 8.314 J mol
1
K
1
,
F
= 96,492 C/mol, and
T
= (
°
C + 273) K
[
]
[
]
o
Cl
i
K
i
Na
i
Cl
o
K
o
Na
m
Cl
P
K
P
Na
P
Cl
P
K
P
Na
P
F
RT
V
+
+
+
+
=
]
[
]
[
]
[
]
[
log
303
.
2
10
y
x
y
y
x
x
m
g
g
E
g
E
g
V
+
+
=
*
*
or alternatively, terms can be rearranged as
V
g
g
E
E
g
g
m
x
y
x
y
x
y
=
+
+
*
1
i
x
=g
x
(V
m
E
x
)
g= 1/R
V=IR
m
i
g
g
=
λ
means “proportional to”
∝
d
g
m
∝
2
d
g
i
∝
V
x
= V
o
* e
(x/
λ
)
e
≈
2.7
Conduction velocity:
λ
∝
CV
Table of log
10
values
1)
20 points
__________
log
10
[
out
]/[
in
]
3
0.001
2
0.01
1
0.1
0
1
1
10
2
100
3
1000
2)
20 points
__________
3)
20 points
__________
4)
20 points
__________
5)
20 points
__________
Total
__________
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Biology 222
Exam 1, Fall 2009
Name__________________________
Page 2
Leave this page blank
Biology 222
Exam 1, Fall 2009
Name__________________________
Page 3
1)
(20 pts)
Information carries over for parts (a) – (c)
a) (6 pts) A space mission to Mars has just returned to Earth but the lead scientist is unable to
continue her work.
Portions of her notebook have been damaged and you are responsible for
reconstructing the data.
Notation above the table says “Properties of Martian neuron at 45 °C.”
Calculate the equilibrium potentials for each ion and give the proper units.
Show your work.
Ion
Outside
Inside
E
x
Na
+
1
100
K
+
130
1.3
Ca
2+
4
0.004
Mg
2+
15
150
Cl

150
15
SO
4
2
0.2
200
b) (4 pts) If the Martian neuron is only permeable to 2 ions and g
x
/g
y
= 1, which 2 ions would
make its V
m
= 0 mV?
Which 2 ions would make its V
m
=
+31.5 mV?
Refer to the table in part
(a) and show your work.
c) (2 pts) The notebook says that g
K
/g
Mg
= 0.25.
What is the V
m
of the Martian neuron
if it is
permeable only to K
+
and Mg
2+
?
Show your work.
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