You isolate four mutant strains of E. coli which are different from the wild type in their metabolism of substances A, B, and C. A, B, and C form a metabolic pathway that is required for the bacteria to grow. Mutant strains and crosses between different mutant strains are plated on a minimal medium with added compounds. You observe the following results, where “+” indicates colonies are observed and “o” indicates no colonies
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. You discover that the mutation in Strain 1 eliminates the functionality of a subunit of a heterodimeric enzyme named M. With respect to the mutations in Strains 2, 3, and 4, select from among the following choices to answer Questions . Place your answer(s) on your scantron.
A. A mutation inactivating a different enzyme than M, one which uses B as a substrate
B. A mutation inactivating a different enzyme than M, one which uses C as a substrate
C. A mutation producing an inactive membrane transport protein for substance A
D. A mutation affecting the same subunit of M that the mutation in strain 1 affects
E. A mutation affecting enzyme M, but a different subunit from that in Strain 1
. What is the most probable choice for the mutation in Strain 2?
What is the most probable choice for the mutation in Strain 3?
. What are the TWO most probable choices for the mutation in Strain 4?