In the initial experiment with S. pneumoniae, why was the extract of smooth (S) cells divided into three tubes?
Understand the Problem
The question refers to a classic experiment, likely Griffith's experiment or a follow-up, involving Streptococcus pneumoniae (S. pneumoniae). In this experiment, scientists were trying to determine the nature of the "transforming principle" that allowed non-virulent (rough or R) bacteria to become virulent (smooth or S). The question asks why the extract from the smooth cells were divided into three tubes, implying that each tube contained an enzyme which removed a different single class of macromolecule.
Answer
The extract was divided to isolate and test whether proteins, RNA, or DNA caused the bacterial transformation.
In the Avery-MacLeod-McCarty experiment, the extract of heat-killed smooth (S) cells was divided into three tubes to selectively destroy proteins, RNA, or DNA. This allowed the researchers to determine which of these molecules was responsible for the transformation of rough (R) cells into S cells.
Answer for screen readers
In the Avery-MacLeod-McCarty experiment, the extract of heat-killed smooth (S) cells was divided into three tubes to selectively destroy proteins, RNA, or DNA. This allowed the researchers to determine which of these molecules was responsible for the transformation of rough (R) cells into S cells.
More Information
The Avery-MacLeod-McCarty experiment followed up on Griffith's experiment. Griffith observed that a substance from heat-killed S strain bacteria could transform R strain bacteria into the virulent S strain.
Tips
It is important to understand the difference between Griffith's experiment and the Avery-MacLeod-McCarty experiment to fully grasp the concept.
Sources
- Isolating Hereditary Material: Frederick Griffith, Oswald Avery, Alfred ... - nature.com
- Avery–MacLeod–McCarty experiment - Wikipedia - en.wikipedia.org
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