BIOL273L Study Guide - Final Guide: Resting Potential, Lumbriculus Variegatus, Oscilloscope

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cerisemole687

16 Oct 2011

School

University of Waterloo

Department

Biology

Course

BIOL273L

Professor

Bruce Wolff

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Document Summary

Lab #1: generation of electrical potentials by an artifical. Hans ussing chamber permeable to cations like na+ and k+ but not anions like. V=0. 199*t*log(a1/a2) activity coefficient: measure of how independently ions behave when dissolved; small at low concentrations, high at high concentrations activity=conc. V = 0. 199 x 293k x log[(0. 001 x 0. 965)/(0. 010 x 0. 902)] Therefore the calculated potential for trial 1 is -56. 6mv. 0: a selectively permeable membrane forces the concentration gradient unable to go from high to low. This causes a difference in charge, similar to the resting membrane potential of a cell: the membrane in this experiment does not have ion channels and k+ and. If k+ didn"t pass very easily through the membrane, the rmp would be closer to -30mv (+60mv for na+, -90mv for k+) but might be offset a little if na+/k+ Atpase was pumping out 3 na+ for every 2k+ in: the activity coefficient is how independently solutes behave in a solution.

Related Questions

Two solutions of KCl are separated by a semipermeable membrane which only allows the diffusion of Clâ ions. The [Clâ] in chamber 1 is 100 mM and the concentration in chamber 2 is 0.1 mM. What is the expected potential difference between the two chambers?

beigecrab294

Huf and Ussing performed experiments where they measured a current flowing between two chambers when each chamber had been filled with a saline solution and the chambers were separated by the skin of a frog. They noted that this current existed whether or not there was a concentration gradient for Na+ ions between the chambers and that Na+ ions and not Li+ moved between the chambers. Explain and describe the source of the current flow.

crimsonpig20

The membrane separating compartments A and B of the followingchamber is permeable only to Clions (gCl = 5). The initialconcentrations of KCl in compartments A and B, before diffusion hasoccurred, are presented below. Use this information to answerquestions 13-18. Note: Whenever necessary, consider compartment Aas the ICF and compartment B as the ECF.

A: KCl = 10 mM B: KCl = 145 mM

13) After equilibrium, the measurable concentration of KCl incompartment A will be:

A) 5 mM.

B) 10 mM.

C) 77.5 mM.

D) 145 mM.

14) After equilibrium, the measurable concentration of KCl incompartment B will be: A) 10 mM.

B) 72.5 mM.

C) 77.5 mM.

D) 145 mM

15) At equilibrium, compartment A will be _____mV (includepolarity) compared to a reference of 0 mV. Consider compartment Bas the outside.

A) 70 mV

B) -70 mV

C) 90 mV

D) -90 mV

16) Increasing the concentration of [Cl- ] in compartment B from145 mM to 180 mM will ______________. Consider compartment B as theoutside.

A) reduce the absolute value of ECl.

B) reduce the absolute value of EK.

C) increase the absolute value of ECl.

D) not change the absolute value of ECl.

17) At equilibrium, the flux of Clfrom compartment A tocompartment B will be ______ the flux of Clfrom compartment B tocompartment A.

A) equal to

B) less than

C) more than

18) If the conductance for Cl- (gCl) is increased from 5 to 10,the equilibrium potential for Cl- will:

A) become larger.

B) become smaller.

C) not change.

greyalligator970

BIOL273L Study Guide - Final Guide: Resting Potential, Lumbriculus Variegatus, Oscilloscope

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