- Without a selectable marker, it becomes difficult to distinguish between recombinant and non-recombinant cells.
- Additional screening methods, such as PCR or DNA sequencing, are needed, which increases time and cost.
List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |