Which statement is true regarding the odor receptor gene family size?

Which statement is true regarding the odor receptor gene family size?

• A. It contains about 350 genes
• B. It contains about 10,000 genes
• C. It contains about 1,000 genes
• D. It contains about 100 genes

Answer: (C)

Odor receptor genes form a large gene family that encodes receptors for detecting a vast array of smells. When we talk about the size of this family, we’re counting all gene loci that encode these receptors, not just those currently making functional proteins. In humans, this family comprises roughly 1,000 gene loci, though only about 400 are functional and the rest exist as nonfunctional remnants (pseudogenes). This mix reflects how the repertoire has expanded to cover many odorants over evolution, while some copies have accumulated mutations and become nonfunctional. The numbers 100, 350, or 10,000 don’t capture the typical scale of this family in a single species as accurately as about 1,000 does.

Odor receptor genes form a large gene family that encodes receptors for detecting a vast array of smells. When we talk about the size of this family, we’re counting all gene loci that encode these receptors, not just those currently making functional proteins. In humans, this family comprises roughly 1,000 gene loci, though only about 400 are functional and the rest exist as nonfunctional remnants (pseudogenes). This mix reflects how the repertoire has expanded to cover many odorants over evolution, while some copies have accumulated mutations and become nonfunctional. The numbers 100, 350, or 10,000 don’t capture the typical scale of this family in a single species as accurately as about 1,000 does.