Amino acid charge in different ph

I have my MCAT this saturday and I am having a brain fart moment. A big one to be honest

So for Amino Acids, I believe pka of COOH portion is around 2 and pka of -NH2 portion is around 9. For acidic condition the charge of a aliphatic amino acid (ie valine, leucine or even phenylalanine) is - and then when the environment is neutral (ph=7), the charge is zero and when the environment is basic the charge is +.

Now my question is what's the environment pH range for having the aliphatic...

Amino acid charge in different ph