Go from wide to long format - comma separated columns

I have a data frame that contain multiple comma separated "genes" in column "Symbols". These belong to one category within " Ontology". I would like to split the genes into individual rows, keeping the ontology for each row. Please see my example:

I tried something like this:

reshape(df, direction = "long", varying = list(names(df)[2:2]), v.names = "Symbols",  idvar = c("Term"))


 Term        Symbols
 GO:0003012  TNNI1,STAC3,FKBP1A


 GO:0003012   TNNI1
 GO:0003012   STAC3
 GO:0003012   FKBP1A
 GO:0003013   BDKRB2
 GO:0003013   CASQ2
 GO:0003013   COMP
 GO:0003013   ENO1