How Is the Acidity or Basicity of Amino Acids Determined?

[jones106]

How can you tell if a given amino acid is acidic or basic? I'm lost here. My first thought would be to look at the pKa values. There is virtually no difference in the pKa values for the carboxyl groups; all range from 1.82-2.38. The same goes for the pKa values of the amino groups; all range from 8.8-10.96. Is it the pKa of the R group that determines whether they are acidic or basic? I'm staring at this table, and it only has pKa values for the R groups of 7 of the amino acids.

Thanks very much,
Taylor

 

[chemisttree]

What would happen if there were more acidic groups on an amino acid or more basic groups on an amino acid?