Why might repression of a eukaryotic gene by an RNA be more efficient than repression by a protein repressor? O Protein repressors only prevent the synthesis of a single splice variant of a gene. O RNA repressors bind directly to nucleotide sequences in genes, preventing their transcription. O Protein repressors are inherently unstable, so they degrade quickly and do not completely repress genes. O Synthesis of RNA repressors is less energetically costly than that of protein repressors.

Why might repression of a eukaryotic gene by an RNA be more efficient than repression by a protein repressor? O Protein repressors only prevent the synthesis of a single splice variant of a gene. O RNA repressors bind directly to nucleotide sequences in genes, preventing their transcription. O Protein repressors are inherently unstable, so they degrade quickly and do not completely repress genes. O Synthesis of RNA repressors is less energetically costly than that of protein repressors.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 9TYU: A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous...

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A mutation in the trp repressor gene that prevents the apo-repressor from binding the co-repressor What is the correct option from the choices below? causes the Trp repressor to permanently bind the trp operator. leads to a high level of transcription initiation from the trp promoter, even when tryptophan is present in the medium. does not lead to a high concentration of mRNA molecules that code for the structural genes trp E, D, C, B, A, when tryptophan is present in the medium, because attenuation of the operon will still work. a and b, but not c b and c, but not a
Which of the following functions are characteristic of general transcription factors in eukaryotes? Hint: there may be more than one correct response. Be sure to check all that apply. They inhibit RNA polymerase binding to the promoter and begin transcribing. They bind to other proteins or to the TATA box. They are sufficient to allow high levels of transcription. O They initiate and regulate the transcription of genes. O They bind to sequences just after the start site of transcription.
Below is a model of a signal transduction pathway that results in the transcribing of mRNA: Receptor protein Transcription factor Phosphorylation cascade DNA mRNA What is the best description of what would happen if the phosphorylation cascade resulted in a phosphate being attached to the transcription factor? O mRN would not stop being transcribed from the DNA. O The phosphorylation cascade would continue to release excess phosphates. O mRNA would stop being translated from the DNA. O Receptor proteins would not bind to the signaling hormone.
Which of the following is a property or characteristic of eukaryotic promoters? They contain the -10 and-35 consensus sequences where RNA polymerase holoenzyme, containing the sigma factor, bind to initiate transcription. | They contain the -10 and -35 consensus sequences that are the site where general transcription factors bind to help RNA polymerase holoenzyme initiate transcription. They contain a TATA box to which sigma factors bind to help RNA polymerase core enzyme initiate transcription. O I. They are usually located far away from the gene that is being transcribed. IV. OV. A, They are bound by general transcription factors, which help RNA polymerase I, II, or III, bind to the promoter and initiate transcription.
The lac operon of E. coli controls the expression of genes that code for enzymes involved in lactose metabolism. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I - = produces a repressor protein that cannot bind to the operator region IS = produces a repressor protein that cannot be removed from the operator region OC = cannot bind a repressor protein Z - = produces a defective (non-functioning) β-galactosidase enzyme + = wild type Detail the functionality of the lac operon under the following genetic and cellular conditions. You do not need to consider the role of CAP in your analysis. Genes Repressed (yes/no) Constitutive (yes/no) I+ OC Z+ I+ O+ Z+ (Lactose present) I- O+ Z+
Escherichia coli is grown in the presence of 20 mg of glucose and 20mg of lactose as carbon sources. The major carbon source is consumed by Escherichia at a rate of 10 mg/hour. Which of the following best describes the actions of RNA polymerase, the promoter and the sugar being used after 3 hours? O The sugar binds to the repressor, inactivating it, allowing RNA polymerase to bind to the operator. O RNA polymerase binds to the promoter and the sugar binds to the operator. O The sugar binds to the repressor, inactivating it, and allows RNA polymerase to bind to the promoter. O The sugar binds to RNA polymerase and the repressor binds to a structural gene. Question 41 A Moving to the next question prevents changes to this answer. 61
The lac operon of E. coli controls the expression of genes that code for enzymes involved in lactose metabolism. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I - = produces a repressor protein that cannot bind to the operator region IS = produces a repressor protein that cannot be removed from the operator region OC = cannot bind a repressor protein Z - = produces a defective (non-functioning) β-galactosidase enzyme + = wild type Detail the functionality of the lac operon under the following genetic and cellular conditions. You do not need to consider the role of CAP in your analysis. Genes Repressed (yes/no) Constitutive (yes/no) IS O+ Z+ IS OC Z+
Which of the following are ways in which transcriptional repressors can function in eukaryotes? (Mark all correct answers) Competition with an activator for binding to an enhancer Recruit co-repressors that prevent the RNA Pol II complex from binding the promoter Sequester activators outside of the nucleus Recruit co-repressors that cause heterochromatin formation
Choose all that apply regarding gene transcription in eukaryotes: Multiple transcription factors are necessary to form the pre-initiation complex (PIC) of RNA Pol II. The 5' cap of mRNA requires the free triphosphate on the nucleotide at the 5' end. Introns must be removed from the initial RNA transcipt. Histone acetylation is a method controlling gene expression. Acetylation creates more positive charges on histones, leading to tighter binding of the proteins to DNA. Exons are removed from mRNA by the spliceosome. RNA polymerase II must completely finish an mRNA transcript before processing can begin. RNA polymerase I catalyzes the synthesis of the majority of ribosomal RNA. The hormone 173-estradiol binds to a G-protein coupled receptor to control gene transcription.
What role does an operator sequence serve in bacterial gene expression regulation? Describe one change in bacterial cells that can cause a repressor protein to go from inactive to active or from active to inactive.
What would happen to the regulation of the tryptophan operon in bacterial cells that express a mutant form of the tryptophan repressor that (1) cannot bind to DNA, (2) cannot bind tryptophan, or (3) binds to DNA even in the absence of tryptophan?
Tonly in cell biology the Lac operon in bacteria encodes proteins required to import and digest the disaccharide lactose in the absence of glucose. Lac operon is highly expressed only when two conditions are met: glucose must be absent and lactose must be present. Bacteria solves this issue by employing both an activator and a repressor for the same operon. But how? A Bacteria can turn on Lac operon even if the repressor is bound to the operator region. B When the two conditions are met repressor will not be present, activator will be active. Thus the operon will be ON. C Operon is always on when the repressor is not bound. D Operon will be off when the activator is bound and repressor is not. E Activators itself inhibit repressors from binding to operators.