What does the sequence of bases within a gene specify?

The sequence of bases within a gene specifically encodes the sequence of amino acids in a polypeptide chain. This is fundamental to the process of protein synthesis. Each set of three bases, known as a codon, corresponds to a specific amino acid or a stop signal during translation. Therefore, the linear sequence of nucleotides in the gene directly determines the order in which amino acids are added to form a polypeptide. This specificity is crucial because the unique sequence of amino acids will determine the structure and function of the resulting protein.

The other options, while related to cellular components, do not accurately describe the role of a gene's base sequence. The type of sugar in a molecule, the energy yield of a protein, and the structure of cellular membranes are influenced by various factors but are not directly specified by the nucleotide sequence of a gene.