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Exam 1 2009

# Exam 1 2009 - Biology 222 Page 1 Exam 1 Fall 2009 Name This...

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Biology 222 Exam 1, Fall 2009 Name__________________________ Page 1 This exam is double-sided. Put your first and last name on every sheet! Every sheet missing your name will lose 1 point. Answer all questions on pages 3-12. 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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