If the string of beads refer to a chromosome, then each bead is a gene responsible for one or more traits.
If the string of beads refer to a gene, then each bead refers to the sequence of nitrogenous bases in one strand of the gene.
Explanation:
A chromosome is composed of several genes.
A gene is composed of several nucleotides each containing a nitrogenous base. A gene is primarily made functional by the sequence of nitrogenous bases in its structure. If AGATTCA is a hypothetical sequence of the nitrogenous bases on one strand of a hypothetical gene then TCTAAGT will be the sequence of nitrogenous bases on the complementary strand of that particular gene.
