What process is probably responsible for the origin of the three parts of the constant portion of the IgG heavy chain?
A)inversion of an ancestral gene coding for an Ig unit about 110 amino acids long
B)duplication of an ancestral gene coding for an Ig unit about 110 amino acids long
C)deletion of an ancestral gene coding for an Ig unit about 110 amino acids long
D)point mutation of an ancestral gene coding for an Ig unit about 110 amino acids long
E)nonsense mutation of an ancestral gene coding for an Ig unit about 110 amino acids long

Question

Quizplus · Accepted Answer

Duplication of an ancestral gene coding for an Ig unit about 110 amino acids long is the most likely process responsible for the origin of the three parts of the constant portion of the IgG heavy chain. This duplication would result in three repeated units, which could then evolve separately to form the three distinct constant regions found in IgG heavy chains. Inversions, deletions, point mutations, and nonsense mutations would not result in the same pattern of repeated units.

What Process Is Probably Responsible for the Origin of the Three