Which of the following is not one of the 20 standard amino acids which are the building blocks of proteins, but is in fact sometimes found in proteins?
A) citrulline
B) ornithine
C) selenocysteine
D) xanadine

Question

Quizplus · Accepted Answer

Selenocysteine is not one of the 20 standard amino acids but is considered the 21st amino acid, as it is incorporated into some proteins in a specific manner.

Which of the Following Is Not One of the 20