What is a gene?

• A. A sequence of nucleotides
• B. A chromosomal region
• C. A type of protein
• D. A unit of heredity that codes for a function or product

Answer: (D)

A gene is a unit of heredity that codes for a function or product. Genes are stretches of DNA on a chromosome that contain the instructions to make a molecule, usually a protein or a functional RNA, using transcription and translation. This is why genes are the hereditary units responsible for particular traits. While a gene is built from nucleotides, and a chromosomal region can include many elements, the essential idea is the gene’s role as the coded instruction for a product. The other options miss this idea: a sequence of nucleotides is materiaI rather than the functional unit, a chromosomal region is too broad, and a protein is a product, not the informational unit itself.