The number of peptide bonds in the compound is:

Assertion $(A)$: An optically active amino acid can exist in three forms depending on the $pH$ of the solution.
Reason $(R)$: Amino acids contain both acidic and basic groups; they exist as a zwitterion in aqueous medium,anionic form in basic medium,and cationic form in acidic medium.

The cell membrane is primarily composed of ...........

Consider the following statements:
Statement-$I$: Lysine and arginine are essential and basic amino acids.
Statement-$II$: Leucine and phenylalanine are non-essential and neutral amino acids.

Describe the term $D$ and $L$ configuration used for the amino acids with examples.

The number of disulphide linkages present in insulin are