• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Social distancing? Try a better way to work remotely on your online files. Dokkio, a new product from PBworks, can help your team find, organize, and collaborate on your Drive, Gmail, Dropbox, Box, and Slack files. Sign up for free.

View
 

Electric potential in a cell membrane

Page history last edited by Joe Redish 5 years, 9 months ago

8.3.P1

 

The inner and outer surfaces of a cell membrane carry a negative and positive charge respectively. Because of these charges, a potential difference of about 70 mV exists across the membrane. The thickness of the membrane is 8 nm.

 

  1. If the membrane were empty (filled with air), what would the magnitude of the electric field inside the membrane?
  2. If the dielectric constant of the membrane is k = 3 what would the field be inside the membrane?
  3. Cells can carry ions across a membrane against the field ("uphill") using a variety of active transport mechanisms. One mechanism does so by using up some of the cell's stored energy converting ATP to ADP. How much work does it take to carry one sodium ion (charge = +e) across the membrane against the field? Calculate your answer in eV, Joules, and KCal/Mole (the last for 1 Mole of sodium ions).

 

 

Joe Redish 10/16/02

Comments (0)

You don't have permission to comment on this page.