4 replies to this topic

[JP_]

Could someone explain why gel electrophoresis buffers need to be conductive and thus contain free ions? Why is it not sufficient simply to have opposite charges on the 2 electrodes, and these charges create the electric field to migrate the DNA?  I realize this doesn't work, just can't figure out why

[nightingale]

Quote

Why is it not sufficient simply to have opposite charges on the 2 electrodes, and these charges create the electric field to migrate the DNA?

how will be conduction of charges between the two electrodes if there won't be a media that offers this ???
imagine that u put two electrodes, how will the electrons move between
both if there is no wire between them ??

in our case, instead of the wire ... we have the buffer with the ions.
which acts to convey the electric field which will aid in moving our DNA on the gel ...

hope my notes, make sense to you ...

Edited by nightingale, 05 February 2010 - 12:47 AM.

[JP_]

Quote

how will be conduction of charges between the two electrodes if there won't be a media that offers this ???
imagine that u put two electrodes, how will the electrons move between
both if there is no wire between them ??

I guess my question really is, why do you need an electric current to create the field?

[bob1]

You don't need "electricity", you can use ionic strength, pH... etc.  Have a look at iso-electric focusing.

[Mazhar Hussain]

Dear,
Electric field can also present between both of the poles keeping the air between electrodes....
But air is not conductor it will act as an insulator... Electric field will be more strong in vacuum... Keeping the poles very close to each other.... In the case of buffer... Electric current is constant at each point between the electrodes... Producing a drifting force on each DNA molecule to move it from -ve to +ve... That force is electric field....