$A$ nanopeptide contains .... peptide linkages.

Which is the most abundant protein in the animal kingdom?

Which is the correct option for sulphur-containing amino acids?

Which structure of protein is linear and contains only peptide bonds?

$A$: The properties and types of amino acids vary.
$R$: The chemical structure of amino acids differs due to the $R$ group.

What is the full name of the chemical group represented by $NH_{2}$?