A 'super repressor' mutation in the lac operon, designated Is, results in a lac repressor that cannot bind to allolactose. What is the phenotypic consequence of this mutation?
Explanation
The Is mutation is a classic example of a dominant negative or gain-of-function mutation where the protein is 'stuck' in its repressive state, leading to a permanently off operon.
Other questions
What is the term for the complete collection of RNA molecules in a cell, which includes protein-coding mRNAs, functional non-coding RNAs, and their various forms from processes like editing and splicing?
Which level of gene regulation is affected by how tightly DNA is packaged, which in turn influences how easily transcription machinery can access a gene?
In prokaryotic transcription, what is the term for a promoter that has a sequence closely matching the -10 and -35 consensus sequences, leading to high levels of transcription?
What is the name of the process where a transcription factor increases the rate of transcription from a promoter?
In eukaryotes, what is the function of the large protein complex called the mediator?
What is a polycistronic RNA, a feature often found in prokaryotic gene regulation?
In the lac operon of E. coli, what is the direct role of allolactose?
What is the state of the lac operon regulatory proteins (LacI repressor and CAP) when an E. coli cell is in an environment with high glucose and no lactose?
In the lambda phage life cycle, the lambda repressor (λCI) can act as both an activator and a repressor. What does λCI repress?
What is the mechanism of transcriptional attenuation in the trp operon when tryptophan levels are low?
Why is ribosome-mediated transcription attenuation a mechanism of gene regulation that is unique to prokaryotes?
What would be the effect on the expression of the lac operon from a loss-of-function mutation in the gene for adenylate cyclase?
Considering the lac operon genotype I+, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with no glucose and no lactose?
Considering the lac operon genotype I+, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with high glucose and high lactose?
For the lac operon genotype I+, Oc, Z+, Y+ (a constitutive operator mutation), would beta-galactosidase be expressed if the E. coli were grown in a medium with high glucose and no lactose?
How does the negative autoregulation of the lambda repressor (λCI) work at high concentrations?
What is the term for a DNA element that is part of an operon and is specifically recognized by a repressor protein?
Which statement accurately describes the function of the structural genes in the lac operon?
What type of mutation is a change in the DNA of a gene's promoter that prevents a repressor from binding?
In the lambda phage, what triggers the switch from the lysogenic to the lytic cycle?
Which of the following describes the collection of proteins present in a cell, including those that have been modified post-translationally?
Which of the following is NOT listed as a level at which gene expression can be regulated in a cell?
What is the key difference in translation initiation that prevents eukaryotes from having polycistronic mRNAs like prokaryotes?
What is the role of the sigma factor in prokaryotic transcription initiation?
What is the level of transcription of the lac operon in an E. coli cell with the genotype I+, O+, Z+, Y+ when grown in a medium containing no glucose but high levels of lactose?
In a partial diploid E. coli with the genotype I- O+ Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the presence of lactose?
In a partial diploid E. coli with the genotype I+ Oc Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the absence of lactose?
The lac operon promoter (lacP) is described as a weak promoter. What does this imply about its sequence?
What is the primary role of the protein product of the lacY gene in E. coli?
What structural feature of the trp operon's leader RNA allows it to form a terminator hairpin?
What would be the likely effect of a mutation that changes the two tryptophan codons (UGG) in the trp operon leader sequence to two stop codons (UGA)?
The genes of the lac operon are transcribed into a single polycistronic RNA, but they are translated into separate proteins. How is this achieved in prokaryotes?
What is the function of the catabolite activator protein (CAP) in the regulation of the lac operon?
Which term describes a mutation in the lac operon's operator DNA that prevents the repressor from binding?
The lambda repressor (λCI) protein exhibits cooperative binding to its operator sites. What does this mean?
What is the primary difference between the lytic and lysogenic cycles of a bacteriophage like lambda?
Considering the lac operon genotype Is, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with no glucose and high lactose?
What type of molecule is the product of the lacI gene?
What is the function of the C-terminal domain of the lambda repressor (λCI) protein?
Which statement best describes a 'constitutive mutation' in the context of the lac operon?
How do eukaryotes typically achieve co-regulation of genes that are located on different chromosomes?
What is the integrated viral DNA sequence called during the lysogenic cycle of a bacteriophage?
In the trp operon attenuation system, what is the role of the 2-3 hairpin structure that can form in the leader RNA?
What happens to the lac operon when an E. coli cell is in an environment where both the lac repressor and the CAP activator can bind to their respective DNA sites?
What is the molecular signal that indicates low glucose levels to the lac operon's regulatory system?
Why is the lac repressor described as an allosteric protein?
What is the function of the promoter PR in the lambda phage genome?
In a partial diploid E. coli with the genotype Is O+ Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the presence of lactose?
If a mutation changed the tryptophan codons (UGG) in the trp leader sequence to cysteine codons (UGC), what would be the impact on the transcription of the trp operon?