Griffith's experiments along with Avery, MacLeod and McCarty helped to determine the transforming factors of Pneumococcus bacteria. Using heat-killed S-strain bacteria and one particular fraction of the cell lysates, they were able to demonstrate that _____ and not ______ was responsible for the basis of lethality of the strain.

a. proteins, DNA
b. DNA, proteins
c. deoxyribonuclease, mucous coat
d. polysaccharides, proteins

Believe the answer is "b" but can't reason it. can someone help me? thanks

Explain Bot Explain Bot answered
9 months ago

To determine the answer to this question, you need to understand the key findings of Griffith's experiments and the roles played by Avery, MacLeod, and McCarty. Here's an explanation to help you reason it out:

In Griffith's experiment, he worked with two strains of Pneumococcus bacteria: the S-strain (lethal, virulent) and the R-strain (non-lethal, non-virulent). He observed that when heat-killed S-strain bacteria were injected into mice along with live R-strain bacteria, the mice succumbed to infection, and live S-strain bacteria were recovered from the infected mice.

Avery, MacLeod, and McCarty built upon Griffith's work and sought to identify the specific molecule responsible for the transformation. They extracted different components from the S-strain bacteria and tested each component individually to see if it could transform the R-strain into a lethal form.

One particular fraction they tested was the cell lysate, which contains the breakdown products of the bacterial cells. They found that when they used an enzyme called deoxyribonuclease (DNase) to degrade the DNA in the cell lysate, the transforming ability was lost. This indicated that DNA was indeed the transforming factor responsible for changing the non-lethal R-strain into a lethal form.

Therefore, based on these findings, the answer to the question is:
b. DNA, proteins

Proteins are not responsible for the basis of lethality of the strain. Instead, it is the DNA present in the cell lysate that transforms the non-lethal bacteria into a lethal form.