When $\mathrm{\alpha }$ -amino acid molecules polymerise to form proteins the monomers are connected. The incorrect one regarding the connecting bond is :

Amino acids are building blocks of proteins. Amino acids are linked each other through peptide bond which is also called an amide bond or $-\mathrm{CO}-\mathrm{NH}-$ bond. There is no $-{\mathrm{NH}}_2$ bond.