Biophysics: Concentration and Electric potential

In summary, the conversation discusses a problem involving a permeable membrane and a singly charged ionic species. The question is what electric potential is needed to maintain a net flux of zero at 37C if the concentration on one side is 25 times that of the other. The suggested equations to use are U = KQq/r and flux = Q/ε, with further suggestions to check out the Debye length in an electrolyte for more relevant information.
  • #1
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Homework Statement



Consider a membrane which is permeable to a singly charged ionic species. If the concentration on one side is 25 times that of the other, what is the electric potential required to maintain a net flux of zero at 37C?

Homework Equations



I'm not sure:
U = KQq/r
flux = Q/ε

The Attempt at a Solution



I was using K * Q * 25Q/R

But I'm getting no where
 
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  • #2
I would check check this out:

http://en.wikipedia.org/wiki/Debye_length

There are a few equations there-in that might be useful to you.

I don't know how rigorous your Biophysics course is, but I remember doing problems like this having to do with modeling the net electric field and potential in the environment around charged DNA backbones and across membranes, and these equations, and the ideas they relate to, are what I used. If I have more time, I'll see if I can be more help than this.

EDIT: In particular, the section on "Debye length in an electrolyte" would be the most relevant to your interests.
 
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  • #3
Thank you, but I don't believe the problem is that in depth. Our course isn't very mathematically heavy , so it's usually basic formulas and whatnot. I just can't think of what to do -.-
 

Related to Biophysics: Concentration and Electric potential

1. What is the difference between concentration and electric potential in biophysics?

Concentration refers to the amount of a substance, such as ions or molecules, present in a given space. Electric potential, on the other hand, refers to the difference in electrical charge between two points. In biophysics, concentration and electric potential are closely related as changes in concentration can lead to changes in electric potential and vice versa.

2. How do changes in concentration affect electric potential in biophysics?

Changes in concentration can lead to changes in electric potential due to the movement of ions or molecules across a membrane. For example, an increase in the concentration of positively charged ions on one side of a membrane will create an imbalance of charges and result in a higher electric potential.

3. What is the Nernst equation and how is it used to calculate electric potential?

The Nernst equation is a mathematical relationship that describes the equilibrium potential of an ion across a membrane. It takes into account the concentration of the ion on both sides of the membrane and the temperature. The equation is often used in biophysics to calculate the resting membrane potential of neurons.

4. How is electric potential measured in biophysics?

Electric potential is measured using techniques such as patch-clamping, which involves inserting a tiny electrode into a cell to measure the voltage across the membrane. Other methods include microelectrode recordings and voltage-sensitive dyes.

5. Can changes in concentration and electric potential affect biological processes?

Yes, changes in concentration and electric potential can affect many biological processes, including the movement of ions and molecules across membranes, nerve impulses, and muscle contractions. Maintaining the appropriate balance of concentration and electric potential is crucial for proper cellular function.

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