Chapter 20, Problem 20.21EP

(a)

Interpretation Introduction

Interpretation: The number of carboxyl groups and amino groups present in polar neutral amino acids has to be stated.

Concept introduction: Amino acid is a compound that is composed of ${\text{NH}}_{\text{2}}$ (amino) group and $\text{COOH}$ (carboxylic acid) group.  On the basis of the nature of the side chain, the amino acids are classified as nonpolar, polar neutral, polar acidic, polar basic.

(b)

Interpretation Introduction

Interpretation: The number of carboxyl groups and amino groups present in polar acidic amino acids has to be stated.

Concept introduction: Amino acid is a compound that is composed of ${\text{NH}}_{\text{2}}$ (amino) group and $\text{COOH}$ (carboxylic acid) group.  On the basis of the nature of the side chain, the amino acids are classified as non-polar, polar neutral, polar acidic, polar basic.