Which of the following statements about the globin gene family is true?

Question

(a) The globin protein, which can carry oxygen molecules throughout an organism's body, was first seen in ancient vertebrate species about 500 million years ago.
(b) The gene duplication that led to the expansion of the globin gene family led to the separation and distribution of globin on many chromosomes in mammals, such that no chromosome has more than a single functional member of the globin gene family.
(c) As globin gene family members diverged over the course of evolution, all the DNA sequence variations that have accumulated between family members are within the regulatory DNA sequences that affect when and how strongly each globin gene is expressed.
(d) Some of the duplicated globin genes that arose during vertebrate evolution acquired inactivating mutations and became pseudogenes in modern vertebrates.

Answer 1

Choice (d) is correct. Globin proteins have been found in insects, primitive fish, and marine worms in addition to vertebrates [making choice (a) incorrect]. Gene duplication does not necessarily mean distribution among chromosomes, and in humans, the ?-globin genes are located in a cluster on Chromosome 11 while the ?-globin genes are on Chromosome 16 [choice (b)]. Mutations have occurred in both the regulatory DNA sequences and within the protein-coding regions of the globin genes [choice (c)].