Answer: Streptococcus pneumoniae.
- A Streptococcus pneumoniae
- B Escherichia coli strain K
- C Salmonella typhimurium
- D Bacillus subtilis strain
Correct answer: A. Streptococcus pneumoniae
Explanation: Griffith worked with Streptococcus pneumoniae, where heat-killed virulent bacteria transformed live non-virulent bacteria into the virulent form.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.