When monoaminodicarboxylic amino acids exist in a buffter so

When monoamino-dicarboxylic amino acids exist in a buffter solution of pka 7, what is the overall charge and why?

a) The overall molecule is positively charged

b) The overall molecule is negatively charged

c) The overall molecule is electrically neutral

d) Nono of the above

Solution

b) The overall molecule is negatively charged

Since at neutral pH amine have positive charge and carboxylic acid have negative charge.

Since there is one amine and 2 carboxylic acid group; the overall charge is -1 (negatively charged)