Which of the following is polymerized to form proteins?

An insulin molecule consists of ........ amino acids.

Describe the primary, secondary, and tertiary structures of proteins. $OR$ Describe the structure of proteins.

Which is the most abundant protein in the animal kingdom?

$S$ - Statement: The amino acid with a non-polar $R$ group is serine.
$R$ - Reason: The amino acid with a polar and uncharged $R$ group is threonine.

Which group is present at the $N$-terminal of a polypeptide chain?