TLS Online TPP Program

#Question id: 15655


You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. Next you isolate a mutation, designated MelB–, which gives uninducible melibiase activity. Mapping experiments show that MelB– is linked to Mel1. Using an F' factor that carries the chromosomal region surrounding Mel1, you perform the following genetic tests:

 
Describe the proposal for the type of regulatory functions affected by the MelB– mutation.

#Unit 13. Methods in Biology
  1. MelB is likely a positive regulator of Mel1 expression.
  2. MelB is likely a negative regulator of Mel1 expression.
  3.  MelB is likely a induced regulator of Mel1 expression.
  4. MelB is likely a constitutive regulator of Mel1 expression.