Overview of Gene Regulation
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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?
View answer and explanationWhich level of gene regulation is affected by how tightly DNA is packaged, which in turn influences how easily transcription machinery can access a gene?
View answer and explanationIn 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?
View answer and explanationWhat is the name of the process where a transcription factor increases the rate of transcription from a promoter?
View answer and explanationIn eukaryotes, what is the function of the large protein complex called the mediator?
View answer and explanationWhat is a polycistronic RNA, a feature often found in prokaryotic gene regulation?
View answer and explanationIn the lac operon of E. coli, what is the direct role of allolactose?
View answer and explanationWhat 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?
View answer and explanationA '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?
View answer and explanationIn the lambda phage life cycle, the lambda repressor (λCI) can act as both an activator and a repressor. What does λCI repress?
View answer and explanationWhat is the mechanism of transcriptional attenuation in the trp operon when tryptophan levels are low?
View answer and explanationWhy is ribosome-mediated transcription attenuation a mechanism of gene regulation that is unique to prokaryotes?
View answer and explanationWhat would be the effect on the expression of the lac operon from a loss-of-function mutation in the gene for adenylate cyclase?
View answer and explanationConsidering 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?
View answer and explanationConsidering 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?
View answer and explanationFor 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?
View answer and explanationHow does the negative autoregulation of the lambda repressor (λCI) work at high concentrations?
View answer and explanationWhat is the term for a DNA element that is part of an operon and is specifically recognized by a repressor protein?
View answer and explanationWhich statement accurately describes the function of the structural genes in the lac operon?
View answer and explanationWhat type of mutation is a change in the DNA of a gene's promoter that prevents a repressor from binding?
View answer and explanationIn the lambda phage, what triggers the switch from the lysogenic to the lytic cycle?
View answer and explanationWhich of the following describes the collection of proteins present in a cell, including those that have been modified post-translationally?
View answer and explanationWhich of the following is NOT listed as a level at which gene expression can be regulated in a cell?
View answer and explanationWhat is the key difference in translation initiation that prevents eukaryotes from having polycistronic mRNAs like prokaryotes?
View answer and explanationWhat is the role of the sigma factor in prokaryotic transcription initiation?
View answer and explanationWhat 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?
View answer and explanationIn 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?
View answer and explanationIn 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?
View answer and explanationThe lac operon promoter (lacP) is described as a weak promoter. What does this imply about its sequence?
View answer and explanationWhat is the primary role of the protein product of the lacY gene in E. coli?
View answer and explanationWhat structural feature of the trp operon's leader RNA allows it to form a terminator hairpin?
View answer and explanationWhat 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)?
View answer and explanationThe 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?
View answer and explanationWhat is the function of the catabolite activator protein (CAP) in the regulation of the lac operon?
View answer and explanationWhich term describes a mutation in the lac operon's operator DNA that prevents the repressor from binding?
View answer and explanationThe lambda repressor (λCI) protein exhibits cooperative binding to its operator sites. What does this mean?
View answer and explanationWhat is the primary difference between the lytic and lysogenic cycles of a bacteriophage like lambda?
View answer and explanationConsidering 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?
View answer and explanationWhat type of molecule is the product of the lacI gene?
View answer and explanationWhat is the function of the C-terminal domain of the lambda repressor (λCI) protein?
View answer and explanationWhich statement best describes a 'constitutive mutation' in the context of the lac operon?
View answer and explanationHow do eukaryotes typically achieve co-regulation of genes that are located on different chromosomes?
View answer and explanationWhat is the integrated viral DNA sequence called during the lysogenic cycle of a bacteriophage?
View answer and explanationIn the trp operon attenuation system, what is the role of the 2-3 hairpin structure that can form in the leader RNA?
View answer and explanationWhat 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?
View answer and explanationWhat is the molecular signal that indicates low glucose levels to the lac operon's regulatory system?
View answer and explanationWhy is the lac repressor described as an allosteric protein?
View answer and explanationWhat is the function of the promoter PR in the lambda phage genome?
View answer and explanationIn 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?
View answer and explanationIf 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?
View answer and explanation