Biology · Principles and Processes in Biotechnology

What is the biological significance of insertional inactivation of the \( \beta \)-galactosidase gene in screening recombinant colonies?

1. It ensures that the plasmid lacks any autonomous origin of replication
2. Colonies with recombinant DNA produce blue colour with chromogenic substrate
3. Non-recombinants produce blue coloured colonies while recombinants are colourless
4. It increases the copy number of the vector manifold