21.1 Why bacteria are useful in biotechnology

Bacteria are useful in biotechnology and genetic modification because of their RAPID REPRODUCTION RATE (dividing every ~20 minutes → trillions in 12 hours) and their ABILITY TO MAKE COMPLEX MOLECULES (proteins, hormones, antibiotics) using ribosomes that can read inserted human genes — exemplified by recombinant human insulin produced in E. coli since 1982. HL extension: two additional reasons — FEW ETHICAL CONCERNS (bacteria are not sentient, no welfare laws apply) and the PRESENCE OF PLASMIDS (small circular DNA outside the chromosome that scientists can cut open with restriction enzymes, insert a target gene, ligate, and transform back into bacteria).