Which statement best defines a gene?

Which statement best defines a gene?

• A. A molecule that stores energy.
• B. An organelle within the cell.
• C. A sequence of RNA that transmits signals.
• D. A unit of heredity that occupies a locus on a chromosome and codes for a functional product.

Answer: (D)

A gene is the basic unit of heredity: a specific segment of DNA that sits at a defined location (a locus) on a chromosome and contains the instructions to produce a functional product. That product can be a protein or a functional RNA molecule, and its creation is what links a gene to a trait or cellular function. This captures both the heritable nature of genes and their role in guiding building blocks or regulators inside the cell. The other statements miss key parts of what a gene is. One describes an energy-storing molecule, which is not about heredity. Another points to an organelle, a cell structure, not a unit of inheritance. The last focuses on an RNA sequence that transmits signals and omits the crucial idea of a specific chromosomal location and a hereditary role.

A gene is the basic unit of heredity: a specific segment of DNA that sits at a defined location (a locus) on a chromosome and contains the instructions to produce a functional product. That product can be a protein or a functional RNA molecule, and its creation is what links a gene to a trait or cellular function. This captures both the heritable nature of genes and their role in guiding building blocks or regulators inside the cell.

The other statements miss key parts of what a gene is. One describes an energy-storing molecule, which is not about heredity. Another points to an organelle, a cell structure, not a unit of inheritance. The last focuses on an RNA sequence that transmits signals and omits the crucial idea of a specific chromosomal location and a hereditary role.