Q1. The hypothetical fox operon includes the sequences: foxA, foxB, foxC and fox
ID: 273830 • Letter: Q
Question
Q1. The hypothetical fox operon includes the sequences: foxA, foxB, foxC and foxD. These sequences may represent either structural genes or regulatory sequences. Regulation of expression of the fox operon depends on the compound Fox. The fox operon encodes enzyme 1 and enzyme 2. Levels of activity of these enzymes were measured in a wildtype and mutant strains, as shown in the table (all are loss-of-function mutants): Genotype wildtype foxA- Fox compound absent Enzyme 1 activity Enzyme 2 activity zero zero zero zero zero zero zero Zero zero zero zero zero zero high high Fox compound present Enzyme 1 activity Enzyme 2 activity high high zero high zero zero Zero zero high high zero zero high high high high Zero foxB- foxC- foxD- a) Is the fox operon inducible or repressible? Explain your answer. b) Which sequence from foxA, foxB, foxC and foxD is the: Structural gene for enzyme 1 Structural gene for enzyme 2 Promoter Operator c) Is regulation of the fox operon via a positive or negative mechanism? Explain your answer. d) (You need to use your answer to (c) to answer this part.) If the protein that binds the operator is encoded by the foxR gene, complete another row to the table above for a foxR loss-of-function mutant.Explanation / Answer
A) it is inducible because had it been repressible the presence of the compound would inhibit the activity or expression of the operon
B) fox A codes for enzyme 1
Fox C codes for enzyme 2
Fox B is promoter
Fox D is operator
C) positive, since the presence of the compound expresses the operon
D) it's positively inducible operon which probably means that the protein is a repressor.
If the repressor gene is absent the operon will be induced or expressed whether the compound is present or not.
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