2. Compounds I, II, III are in the following biochemical pathway: Enzyme A Enzym
ID: 3166614 • Letter: 2
Question
2. Compounds I, II, III are in the following biochemical pathway: Enzyme A Enzyme B Enzyme C Precursor ---------> Compound I --------------->Compound II -------------> Compound III Mutation a inactivates enzyme A, mutation b inactivates enzyme B, and mutation c inactivates enzyme C. Mutants, each having one of these defects were tested on a minimal medium to which compound I, II, or III were added. Fill in the results expected from these tests by placing a plus sign (+) for growth or a minus sign (-) for no growth in the following table.
Minimal medium to which is added
Explanation / Answer
Strain with mutation
Compound I
Compound II
Compound III
a
+
+
+
b
-
+
+
c
-
-
+
As “a mutant” cannot convert the precursor to compound I, it cannot grow in media with precursor. As it has all rest functional genes, it can grow all three compounds.
As “b mutant” cannot convert the compound I to compound II, it cannot grow in media with compound I. As it has all rest functional genes, it can grow on compound II and III.
As “c mutant” cannot convert the compound II to compound III, it cannot grow in media with compound I and II. As it has c functional gene, it can grow on compound III.
Strain with mutation
Compound I
Compound II
Compound III
a
+
+
+
b
-
+
+
c
-
-
+
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