Which protein is found in milk?

Amino acids are those which...

Identify the structure of the amino acid shown in the image.

What is the $R$ group present in glycine?

$A$: The polypeptide coil of collagen helix is strengthened by the establishment of hydrogen bonds between the $>NH$ group of the glycine residue of each strand and the $-CO$ group of the other two strands.
$R$: In the collagen helix,a locking effect also occurs with the help of proline and hydroxyproline amino acids.

Select the correct option for the following matches:

List-$I$	List-$II$
$(1)$ Non-polar $R$ group	$(a)$ Tyrosine
$(2)$ Polar positive $R$ group	$(b)$ Glutamic acid
$(3)$ Polar negative $R$ group	$(c)$ Histidine
$(4)$ Polar uncharged $R$ group	$(d)$ Tryptophan