gel electrophoresis vs. isoelectric focusing

[theonlytycrane]

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Are these synonymous? I've been thinking that both separate molecules based on size and charge. I came across a question saying that gel electrophoresis focused purely on size, though.

Maybe I need to revise my thinking that gel electrophoresis is focused more on size separation, whereas isoelectric focusing is more for separation based on pI.

 

[laczlacylaci]

I believe IEF is a sub of electrophoresis.
IEF: sep. based on pI
Electrophoresis: sep. based on size and +/- charge.

According to wiki, IEF is a type of zone electrophoresis.
But I think electrophoresis is more on size.

 

[rhinzaz]

I would think gel electrophoresis to be an umbrella term for the separation of biomolecules, be it DNA, RNA or proteins. IEF is basically gel electrophoresis strictly for PROTEINS along with another dimension or parameter; a pH gradient. So IEF mainly separates proteins based on their pI (strictly when charge is zero). I could also separate proteins based mainly on size; which is another type of gel electrophoresis; which is SDS-PAGE (all proteins have net negative charge). In a basic term gel electrophoresis, the main thing causing the mobility is applied current, and then factor the dimensions that influence the electrophoretic mobility; size, charge, shape etc but note that it is still influenced in part by charge, just not as strictly as IEF.