In which of the following is $Keratin$,a fibrous protein,absent?

The cell membranes are mainly composed of

Which of the following amino acids is not optically active?

Assertion: $\alpha$-amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity.
Reason: $H^{+}$ ion given by carboxylic group $(-COOH)$ is captured by amino group $(-NH_2)$ having lone pair of electrons.

Which of the following is a conjugated protein?

Sanger's reagent is used for the identification of which of the following?