2010 1st Midterm Exam Key

2010 1st Midterm Exam Key - Cellular Neurobiology / BIPN...

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Cellular Neurobiology / BIPN 140 Name__ ______KEY_____________ FIRST MIDTERM EXAMINATION Fall, 2010 GENERAL INSTRUCTIONS 1. Please write your name on ALL 6 pages. 2. Please answer each question IN THE SPACE ALLOTTED. 3. For full credit, state your assumptions and show your calculations. 1) _Michaelanne______/5 pts 2) _Michaelanne______/10 pts 3) _Michaelanne______/10 pts 4) _Joseph______/20 pts 5) _Joseph______/10 pts 6) _André______/25 pts 7) _Vishnu______/10 pts 8) _Vishnu______/10 pts 9) _Vishnu______/10 pts EXTRA CREDIT TOTAL ___________/100 pts WAIVER : By signing this waiver I give permission for this exam to be left for me to pick up in the vestibule by the elevator on the 3rd floor of Pacific Hall. I understand that I may only pick up my own exam. I realize that the Department of Biology and its staff cannot take responsibility for exams, which may be stolen or lost, from this area. If I choose not to sign this waiver, I acknowledge that my exam will only be available for pickup 1:30-2:30 p.m., Monday- Friday from 3100E Pacific Hall. ____________________________________ ______________________________ 1 . a) What is meant by frequency coding of information in the nervous system? 1
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Cellular Neurobiology / BIPN 140 Name__ ______KEY_____________ The strength of the stimulus is encoded in the frequency of action potential firing without changing the amplitude of action potentials. 3 pts b) If we perform an experiment in which we hang weights from an isolated muscle and measure action potential firing in the axon of the sensory neuron innervating one of its stretch receptors, how will changing the weight change the size of the action potentials we record? The size of AP will not change with altered weight. Only the firing frequency will change. 2 pts 2 . a) To what ion is the neuronal membrane primarily permeable at rest? If the external concentration of this ion is 2.5 mM and the internal concentration is 140 mM what is its equilibrium potential at room temperature (~20 degrees C)? Will this calculated potential match the measured resting potential? Why or why not? Would it be more depolarized or hyperpolarized? Potassium ions 2 pts E K = 58 log [K + ] o = -101.4 mV 2 pts [K + ] i No, the equilibrium potential will not match measured resting potential. We will measure a more depolarized potential because the membrane is slightly permeable to other ions that have more positive reversal potentials – principally Na + . 2 pts b) What four components are involved in generating the neuronal resting potential? 1 pt each 1. Intracellular impermeant ions 2. Selectively permeable membrane (permeable to K + ) 3. Concentration difference of K + across the cell membrane 4. Sodium/potassium pump. 3.
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This note was uploaded on 10/30/2010 for the course BIPN BIPN 140 taught by Professor Spitzer during the Fall '07 term at UCSD.

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2010 1st Midterm Exam Key - Cellular Neurobiology / BIPN...

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