earning Catalyticscom Animation 16 One gene makes one prot L

earning Catalytics.com Animation 16: One gene makes one prot Learning Catalytics Chegg Study I Guided Solutions and... DNA Replication I How to take a screenshot on your Ma. Jump to 1 2 3 4 5 6 7 many choice question Mystery Operon (1 of 7) You are investigating a newly discovered operon in bacteria. This operon has two genes that are regulated together under the control of a single promoter and a single transcription factor. There are five regions: 1. A regulatory gene for the transcription factor protein 2. A promoter for the structural genes in the operon 3. A binding site for the transcription factor 4. A structural gene for an enzyme (Gene 1) 5. A structural gene for a channel protein (Gene 2) Expression of the wild-type operon is dependent on an external signal, namely the presence or absence of an amino acid. To determine the function of different regions of this segment of DNA, you make mutations and determine the effect on protein production in the presence and absence of the signal. The results are shown in the table. A plus sign indicates that a functional protein is made; a minus sign indicates that no functional protein is made. Signal No Signal Mutation Enzyme Channel Enzyme Channel None Region A Region B Region C Region D Region E Which statements about the effect of the amino acid signal on the wild-type operon are true? Select all that apply. A. The signal causes the genes to be expressed. B. The signal blocks the genes from being expressed C. This operon is inducible. D. This operon is repressible D Hide response Change response

Solution

Answer is B and D

The operon is usually ON to produce the enzyme. When the amino acid is present, the channel protein is expressed to allow the aminoacid inside so as to bind to the promoter region to stop the expression of enzyme.

So presence of signal (aminoacid) - enzyme not expressed

absence of signal - enzyme is expressed