If you are using a vector with lacZ as a screenable marker, which of the following bacterial strains would you want to use as host cells?
1. lacO-
2. lacI-
3. lacZ-
4. Any of these would work.
In genetic engineering, the antibiotic-resistance gene is used:
1. To select healthy vectors
2. As sequences from where replication starts
3. To keep the cultures free of infection
4. As selectable markers