Question

QUESTION 32 1. Organize the steps of the Avery-MacLeod-McCarty experiment in the correct order:

(A) They treated each tube with a specific enzyme that would degrade one single type of chemical compound. (B) They examined what happened to the mice. (C) They identified the chemical nature of the transforming principle. (D) They took a mixture of the S Strain bacteria and broke the cells up and then separated the mixture into different tubes. (E) They added R strain bacteria to each of the tubes and then injected them to different mice.

a. EDCA b. DAEBC c. CDEA d. ABCDE

Answer 1

The steps of the Avery-MacLeod-McCarty experiment are organized in the correct order as follows.

(D) They took a mixture of the S Strain bacteria and broke the cells up and then separated the mixture into different tubes.

(A) They treated each tube with a specific enzyme that would degrade one single type of chemical compound.

(E) They added R strain bacteria to each of the tubes and then injected them into different mice.

(B) They examined what happened to the mice.

(C) They identified the chemical nature of the transforming principle.

Hence, the correct order of the steps involved in the Avery-MacLeod-McCarty experiment is DAEBC.

Explanation:

Avery, MacLeod, and McCarty conducted an experiment to identify the chemical nature of the transforming principle, discovered by  Frederick Griffith in his experiments. Avery, MacLeod, and McCarty took a mixture of the S Strain bacteria and broke the cells up and then separated the mixture into different tubes. They treated each tube with a specific enzyme that would degrade one single type of chemical compound. They used DNAase that would degrade DNA, RNAase that would degrade RNA and proteinase that would degrade proteins. After adding the enzymes in tubes, they added R strain bacteria to each of the tubes and then injected them into different mice. When they examined the mice, they found that the mice injected with R strain bacteria treated with RNAase and proteinase could not survive. However, the mice injected with R strain bacteria treated with DNAase could survive. From the survival of the mice injected with R strain bacteria treated with DNAase, it was clear that S strain bacteria could not be transformed into R strain as the treatment with DNAase degraded DNA. Hence, Avery, MacLeod, and McCarty identified the chemical nature of the transforming principle as DNA.