What is the purpose of ampicillin in bacterial transformation?

Ampicillin is used in bacterial transformation as a selective agent to identify successfully transformed cells. Plasmids introduced during transformation often contain an ampicillin-resistance gene (bla), which allows transformed bacteria to grow in the presence of the antibiotic. Bacteria that fail to take up the plasmid are unable to survive on ampicillin-containing media, ensuring that only transformed cells are selected for further analysis.