What type of mutation might result in a non inducible lac operon?
An “up” mutation would make the lac operon no longer dependent on the positive regulation by the cAMP‑CAP complex (when the operon is induced). A “down” mutation would not allow expression even in the de‑repressed state (presence of inducer) and hence would show a non‑inducible phenotype.
What are inducible genes?
Inducible genes are those that have variable activity, depending on the needs of the cell. For example, the glucose transporter proteins that muscle cells produce in response to insulin are the product of inducible genes. Insulin stimulates their activity. Silenced genes are those that have been permanently turned off.
What is an example of a inducible operon?
The lac operon is an example of an inducible system. Thus, for the trp operon , the addition of tryptophan (the effector molecule) to the E. coli environment shuts off the system because the repressors binds at the operator.
What does the Lac I gene do?
The LacI gene is a regulatory gene that codes for the lactose-inducible lac operon transcriptional repressor. In other words, it codes for the respressor of te Lac-operon. LacI is always transcribed. When the repressor binds to the operator, the Lac genes can’t be transcribed.
Is lac operon mutation?
Single mutants of the lac operon Such mutant are called constitutive mutants. The operator locus (lacO) – One example is Oc, in which a mutation in an operator sequence and reduces or precludes the repressor (the lacI gene product) from recognizing and binding to the operator sequence.
Is lac an operon?
The lac operon is an operon, or group of genes with a single promoter (transcribed as a single mRNA). The genes in the operon encode proteins that allow the bacteria to use lactose as an energy source.
What happens if lacZ is mutated?
If this cell had alternative carbon sources to use for ATP production, like glucose or some other sugar, then the major consequence of a mutation in the lac Z gene would be the build up of lactose.
What happens if lac operon is mutated?
Cells carrying these mutations also cannot induce expression of the lacY and lacA genes; that is, these mutations prevent expression of the entire lac operon. According to the Jacob and Monod model, such promoter mutations block initiation of transcription by RNA polymerase (see Figure 10-2).