Regarding time, voltage, AMP, needed for RNA electrophoresis, what 6-7 Volt/cm mean in electrophoresis of RNA; how can i determine this?
The centimeter (cm) value here is the distance between the electrodes (some mistakenly take this as the length of the gel). So if the distance between the electrodes is for instance 10 cm, to run at 6 v/cm, you will electrophorese at 60 volts.
I am sorry, but I disagree with Syed. Since the main resistance between the electrodes is provided by the gel, the drop in voltage in the tanks between the electrodes and the edges of the gel is minimal and can be neglected. Therefore, the actual field across the gel is roughly equal to the voltage applied to the electrodes divided by the length of the gel. If you go by Syed's mode of calculation, you will understimate the field strength and risk overheating of the gel.
I highly appreciate for correction. Thank you very much indeed Dr. Pierre.
First of all, I would like to appreciate Dr. Zeinab Aboezz for such a nice question. Actually, Volt/Cm is unit of Electric field in Vacuum. The meaning of 6-7 Volt/cm in electrophoresis of RNA is, a RNA of any size is experiencing force from 6-7 volts between two electrodes which are separated by 1cm. The medium in which RNA experiencing the force could be either vacuum or gel. In vacuum where no resistance, RNA (either smaller of larger size) will move at equal distance but in gel larger size RNA will cover less distance than smaller. 6-7 Volts/Cm = 6-7 volts/1Cm, and as we discussed above that 1 Cm is distance between two electrodes and this is too much less distance. I think this much distance between two electrodes elecrophoresis unit for RNA or DNA running is not useful. Therefore, 6-7 Volts/Cm could be 60-70 Volts/10Cm and both is having same meaning.
Finally, we can conclude that run RNA at 60-70 volts in the electrophoresis unit which electrodes separated by 10 Cm distance.
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