Practice Questions

TLS Online TPP Program

#Question id: 15656

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. Explain the two regulatory pathways for Mel1 that can explain the behavior of the MelA– and MelB– mutations. For each regulatory pathways what is a role for the inducer melibiose?

#SCPH01 Biochemistry

melibiose and MelB both have a net negative effect on Mel1 activity, and MelA has a net positive effect on Mel1 activity.
melibiose and MelB both have a net positive effect on Mel1 activity, and MelA has a net negative effect on Mel1 activity.
melibiose and MelB both have a net positive effect on Mel1 activity, and MelA also has a net positive effect on Mel1 activity.
melibiose and MelB both have a net negative effect on Mel1 activity, and MelA also has a net negative effect on Mel1 activity.