In a classic experiment on bacterial transformation, which molecule was identified as the genetic material responsible for transforming non-virulent Streptococcus pneumoniae into a virulent form?

• A. Lipid
• B. RNA
• C. DNA
• D. Protein

Answer: (C)

Verified step by step guidance

1. Understand the context of the experiment: This classic experiment was conducted by Frederick Griffith in 1928, studying Streptococcus pneumoniae bacteria.
2. Identify the key observation: Griffith found that a substance from heat-killed virulent bacteria could transform non-virulent bacteria into a virulent form, indicating the transfer of genetic information.
3. Consider the candidate molecules: The options include Lipid, RNA, DNA, and Protein. Each of these molecules has different biological roles, but only one carries genetic information.
4. Recall the conclusion from subsequent experiments (Avery, MacLeod, and McCarty, 1944): They demonstrated that DNA is the molecule responsible for transformation, not protein, RNA, or lipids.
5. Summarize the key point: DNA was identified as the genetic material that carries the instructions for virulence, enabling the transformation of non-virulent Streptococcus pneumoniae into a virulent form.