Which of the following is not an amino acid?

In $\text{alanyl-glycyl-leucyl-alanyl-valine}$,the number of peptide linkages is $......$

Which one of the following statements is correct?

Identify the $N$-terminal and $C$-terminal $\alpha$-amino acids respectively in the following polypeptide fragment: $Ala-Gly-Ser-Tyr-Gly$.

What is the process of protein synthesis based on genetic information called?

$A$ tetrapeptide has a $-COOH$ group on alanine. This produces glycine $(Gly)$,valine $(Val)$,phenylalanine $(Phe)$,and alanine $(Ala)$ on complete hydrolysis. For this tetrapeptide,the number of possible sequences (primary structures) with the $-NH_2$ group attached to a chiral center is: