First post here, and this looks like a great place to be!
I take Grade 11 Biology. My textbook says that carrier proteins can bring only non-charged substances through the cell membrane, while channel proteins can bring charged substances through the membrane. Unfortunately, it does not explain these two characteristics.
So my question is: why can’t carrier proteins bring charged substances across the cell membrane?
Best easy explanation that I can give without getting too detailed is that in channel proteins they have polarity that allows them to be embedded in the cell membrane. This polarity allows molecules that are also polar to slip in. In the case of carrier proteins they bond to nonpolar molecules and have to use active transport of some kind to pull the molecule through the membrane. Look this up online and you should find some stuff.