In the primary structure of proteins,the amino acids are interconnected by-

The pair in which both species have iron is

Which of the following acids behaves like a salt in aqueous solution?

The secondary structure of protein is stabilized by:

Assertion $(A)$: In aqueous solution,amino acids exist in dipolar ion form.
Reason $(R)$: Most of the naturally occurring amino acids have $L$-configuration.
The correct option among the following is:

Which of the following is an acidic amino acid?