noun. A section of DNA that contains the genetic code for a single polypeptide and functions as a hereditary unit.

noun. Sometimes used interchangeably with the word gene, a cistron is the unit of hereditary material (e.g. DNA) that encodes one protein.

noun. (genetics) a segment of DNA that is involved in producing a polypeptide chain; it can include regions preceding and following the coding DNA as well as introns between the exons; it is considered a unit of heredity

"They explicitely explain that streptomycin resistance is the result of the organisms singular rRNA cistron, which renders them with one reversible mutation from almost completely resistant/non-resistant."

sequence  

allele  allelomorph  dominant gene  genetic marker  holandric gene