Which among the following is a globular protein?

$A$ tetrapeptide is made of naturally occurring alanine,serine,glycine,and valine. If the $C$-terminal amino acid is alanine and the $N$-terminal amino acid is chiral,the number of possible sequences of the tetrapeptide is $....$

Which of the following is the correct structure of $L$-alanine?

Identify the basic amino acid.

What are the common types of secondary structure of proteins?

The given structure of $\alpha$-amino acid will exist at which $pH$?
$NH_3^+ - CH(R) - COOH$