The Term N-Terminus Refers to the Presence of This at One

Question

The term N-terminus refers to the presence of this at one of the ends of a polypeptide.
A)oxygen atom
B)carboxyl group
C)amino group
D)carbonyl group
E)sulfate group

Accepted Answer

The N-terminus refers to the end of a polypeptide that contains the free amino group (NH2). This is why choice C, amino group, is the correct answer. The carboxyl group (choice B) is found at the C-terminus of a polypeptide. The oxygen, carbonyl, and sulfate groups (choices A, D, and E) are not relevant to the N- or C-termini of a polypeptide.