Which one of the following is most essential for the growth and formation of new cells?

What is the end of a polypeptide chain that contains a free carboxyl group called?

The peptide chains loop,twist and fold back on themselves due to the formation of . . . . . . bonds to form a stable tertiary structure of protein.

If one end of a polypeptide chain contains an $NH_2$ group,what does the other end contain?

Match List-$I$ and List-$II$ with respect to proteins and their functions and select the correct option.

List-$I$	List-$II$
$1$. Collagen	$p$. Fights infectious agents
$2$. Trypsin	$q$. Hormone
$3$. Insulin	$r$. Enzyme
$4$. Antibody	$s$. Intercellular ground substance

Between which groups is a dipeptide bond formed?