Sulphur $(S)$ containing amino acids from the following are:
$(a)$ isoleucine
$(b)$ cysteine
$(c)$ lysine
$(d)$ methionine
$(e)$ glutamic acid

Thyroxine produced in the thyroid gland is an iodinated derivative of

Assertion : At isoelectric point,the amino acid does not migrate under the influence of an electric field.
Reason : At isoelectric point,amino acid exists as a zwitterion.

Which among the following is a source of wool?

Identify the incorrect statement about the tertiary structure of proteins.

$A$ dipeptide,$X$ on complete hydrolysis gives $Y$ and $Z$. $Y$ on treatment with aqueous $HNO_2$ produces lactic acid. On the other hand,$Z$ on heating gives the following cyclic molecule.
Based on the information given,the dipeptide $X$ is: