Briefly describe the types of groups participating in the structure of amino acids.

(N/A) $\Rightarrow$ Amino acids are organic compounds containing an amino group and an acidic group as substituents on the same carbon,i.e.,the $\alpha$-carbon. Hence,they are called $\alpha$-amino acids.
$\Rightarrow$ There are four substituent groups occupying the four valency positions of the $\alpha$-carbon. These are a hydrogen atom,a carboxyl group $(-COOH)$,an amino group $(-NH_2)$,and a variable group designated as the $R$ group.
$\Rightarrow$ The $R$ group in these proteinaceous amino acids can be a hydrogen atom (in glycine),a methyl group (in alanine),a hydroxymethyl group (in serine),etc.
$\Rightarrow$ The chemical and physical properties of amino acids are essentially determined by the amino,carboxyl,and the $R$ functional groups.
$\Rightarrow$ Based on the number of amino and carboxyl groups,amino acids can be classified as acidic (e.g.,glutamic acid),basic (e.g.,lysine),or neutral (e.g.,valine). Similarly,there are aromatic amino acids (e.g.,tyrosine,phenylalanine,tryptophan).
$\Rightarrow$ $A$ particular property of amino acids is the ionizable nature of the $-NH_2$ and $-COOH$ groups. Consequently,in solutions of different pH values,the structure of amino acids changes,forming a zwitterionic structure at a specific pH.