Final answer:
A gene is a segment of DNA that carries a code for making a specific polypeptide chain.
Step-by-step explanation:
A gene is a segment of DNA that carries a code for making a specific polypeptide chain. Genes are responsible for the production of proteins, which are essential for cellular function. Each gene contains the instructions for a single protein, and the sequence of nucleotides in a gene determines the sequence of amino acids in the polypeptide chain.