Which statement best describes a gene?

A gene is best described as a segment of DNA that encodes a specific protein because this definition captures the primary function of a gene in the context of molecular biology. Genes serve as templates for the synthesis of proteins through the processes of transcription and translation. During transcription, the DNA sequence of the gene is transcribed into messenger RNA (mRNA), which then serves as the blueprint for assembling amino acids in the correct order to form a specific protein during translation.

This definition distinguishes genes from other biological molecules such as functional RNA molecules, which may not encode proteins, or types of RNA, which can include several forms with various roles that do not necessarily relate to protein synthesis. While proteins can assist in functions such such as folding, they are the products of gene expression rather than the genes themselves. This understanding of a gene's role as a DNA segment encoding proteins is central to genetic and molecular studies in biology, emphasizing the gene's function in heredity and biotechnology.