What is a characteristic of a gene?

A gene is indeed defined as a segment of DNA that contains the necessary information to code for a protein. This is a fundamental principle of genetics, as genes serve as blueprints for the synthesis of proteins, which play crucial roles in the structure and function of living organisms. Each gene has a specific locus on a chromosome and is responsible for particular traits or characteristics by guiding the production of proteins through the processes of transcription and translation.

Understanding this definition is essential, as it underscores the central role of genes in inheritance and variation among organisms. While many genes are expressed in phenotypes, not all genes are always active or visible, thereby making the statement about a gene being always expressed as a phenotype incorrect. Genes can be inherited from both parents, and environmental influences can affect how they are expressed; therefore, the options regarding inheritance and environmental factors do not accurately represent the characteristics of genes.