The colonies of recombinant bacteria appear white because of:
1. | Insertional inactivation of alpha-galactosidase in non-recombinant bacteria |
2. | Insertional inactivation of beta-galactosidase in recombinant bacteria |
3. | Inactivation of glycosidase enzyme in recombinant bacteria |
4. | Non-recombinant bacteria containing beta-galactosidase |
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