Semi-conservative replication of DNA was first demonstrated in:
- Drosophila melanogaster
- Streptococcus pneumoniae
- Salmonella typhimurium
- Escherichia coli
Answer
(4) Escherichia coli
Solution
As per NCERT, Matthew Meselson and Franklin Stahl (1958) grew Escherichia coli in a medium containing 15NH4Cl and then transferred it to 14NH4Cl medium.
⇒ Hybrid (intermediate density) DNA after one generation and equal hybrid and light DNA after two generations proved that DNA replicates semi-conservatively.
Answer: (4)