It is desirable for certain properties to keep their values unique across all resources, this can be expressed by defining the properties as being a nrl:InverseFunctionalProperty.
ex:geneticInformation a rdf:Property, nrl:InverseFunctionalProperty;
rdfs:domain ex:Eukaryote;
rdfs:range xsd:string;
With that in place, no two resources can have the same value on the property.
# First insertion, this will succeed
INSERT DATA { <drosophila> a ex:Eukariote;
ex:geneticInformation "AGCT" }
# This will fail
INSERT DATA { <melanogaster> a ex:Eukariote;
ex:geneticInformation "AGCT" }