25s

25s is a designation that can refer to multiple concepts across different fields. In everyday notation, "25s" can indicate a duration of 25 seconds, with the letter s standing for seconds in sport timing, experiments, and countdowns.

In biology, "25S" or "25S rRNA" denotes a ribosomal RNA component found in the large ribosomal subunit of many fungi, notably in budding yeast. The 25S rRNA gene is commonly used as a molecular marker in fungal systematics and phylogenetics, because its sequence variation helps distinguish species and infer evolutionary relationships. Genes encoding 25S rRNA are transcribed by RNA polymerase I and are part of the 60S ribosomal subunit; in many fungi the mature rRNA species include 25S, 5.8S, and 5S rRNAs. Because of its conserved and variable regions, 25S rRNA is frequently sequenced in studies of Saccharomyces and related species, and is often analyzed alongside other rRNA genes such as the internal transcribed spacer (ITS) region.

Beyond biology, "25S" can appear in product names, catalog numbers, or model designations that use alphanumeric sizing. The exact meaning depends on the issuing organization or industry context.