Microbio Chapter 7 Quiz

Regulation of an enzyme's activity occurs A) transcriptionally. B) translationally. C) posttranslationally. D) at any point on the enzymatic production pathway.

When arginine is added to a culture growing exponentially in a medium without arginine, what occurs? A) All cellular growth ceases. B) Growth continues, but the production of enzymes required for the synthesis of arginine ceases. C) Growth continues, but the production of enzymes required for the synthesis of arginine increases. D) The cell returns to the lag stage of growth to synthesize the proteins necessary for the metabolism of arginine.

Regulatory proteins A) are influenced by small molecules. B) bind to specific DNA sites. C) regulate transcription. D) regulate transcription, bind specific DNA sites, and can be influenced by small molecules.

A protein region with a specific function and structure is called a A) conserved site. B) domain. C) locale. D) motif.

Transcriptional regulators bind most frequently at the ________ site of DNA. A) major groove B) minor groove C) histone complex D) primary supercoil

Which type of regulator(s) specifically bind to operator regions of DNA? A) activators B) activators and inducers C) repressors D) repressors and corepressors

The lac operon is an example of ________ control in which the presence of an ________ is required for transcription to occur. A) negative / activator B) negative / inducer C) positive / activator D) positive / inducer

Enzyme induction occurs A) when the substrate is present. B) when the organism is environmentally stressed. C) continuously. D) when the substrate is depleted.

Considering the catabolite repression mechanism, which observation would make you suspect it is NOT occurring? A) CRP bound to promoter sites B) elevated levels of transcripts for maltose and sucrose catabolism C) relatively low intracellular cyclic AMP levels D) RNA polymerase bound to biosynthetic promoter sequences

During a growth curve of Aliivibrio fischeri, when would you expect to see the strongest bioluminescence? A) lag phase B) early to middle log phase C) late log to early stationary phase D) middle to late stationary phase

What occurs when an inducer is added to an environment containing an organism with a metabolic pathway controlled by a repressor? A) The inducer combines with the repressor and activates the pathway. B) The inducer combines with the repressor and inactivates the pathway. C) The inducer combines with the substrate and blocks induction. D) The inducer does not combine with, but functions as a chaperone molecule for, the enzyme-substrate complex.

Which of the following do NOT bind to the promoter sequence during regulation? A) activators B) inducers C) repressors D) activators, inducers, and repressors

Cyclic AMP is synthesized from ATP by an enzyme called ________ which is involved in ________. A) adenylate cyclase / catabolite repression B) adenylate cyclase / transcriptional activation C) cAMP receptor protein (CRP) synthase / catabolite repression D) cAMP receptor protein (CRP) synthase / transcriptional activation

In negative control of transcription, how does the presence of an inducer affect transcription? A) The inducer binds to the operator. B) The inducer does not bind to the operator. C) The inducer causes the repressor to bind to the operator. D) The inducer prevents the repressor from binding to the operator.

Which type of regulatory protein(s) is/are present in Archaea? A) Activators that stimulate RNA polymerase activity are present in Archaea. B) Repressors that block RNA polymerase activity are present in Archaea. C) Both activators and repressors are present in Archaea. D) Similar to regulation in Eukarya, Archaea lack bacterial-like regulators such as activators and repressors and use transcription factors instead.

The function of a kinase is A) methylation. B) response regulation. C) phosphorylation. D) glycosylation.

The promoters of positively controlled operons require activator proteins, because A) RNA polymerase easily recognizes the consensus sequence. B) they are required to inactivate the repressor proteins. C) the promoters have nucleotide sequences that bind RNA polymerase weakly, which are not close matches to the consensus sequence. D) they are needed to bind to the allosteric site of RNA polymerase.

To be most sensitive to a repellant, a methyl-accepting chemotaxis protein must be ________ methylated to initiate a ________. A) fully / run B) fully / tumble C) not / run D) not / tumble

19) The most frequent way in which regulatory RNA molecules exert their effects is by A) base pairing with other RNA molecules that have regions of complementary sequence. B) binding to a repressor and repressing enzyme transcription. C) acting as an inducer that then binds to an activator protein to allow transcription to proceed. D) signal transduction.

When a Bacillus anthracis population suddenly must form spores to survive a harsh nutrient poor environment, how do the cells obtain energy? A) Cells in a growth phase that have not used up all of their energy will be the only ones to make endospores, which is why relatively few endospores are often made from a large population. B) Intracellular energy reserves are quickly made available to produce endospores. C) Slow responding cells are cannibalized by others that already began spore formation. D) Global regulation is initiated to minimize energy waste in biosynthetic pathways and catabolic pathways are increased to consume remaining usable substrates to fuel spore formation.

Interpret the results to the following experiment. Transcriptional activity of chemotactic genes showed a high expression level during the following conditions: repelling away from compound 1, moving towards compound 2, and remaining sessile when presented compounds 3 and 4. A) Activity during movement in any direction led to high measurements observed, and the sessile population responded equally to both a chemoattractant and a chemorepellant but remained in the same location for their net movement. B) Gene expression by itself cannot distinguish between cells responding to both an attractant and repellent, so this ambiguity makes transcriptomics unfavorable but nonetheless indicates activity. C) The activity observed during a sessile existence suggests the molecular probe was targeting a chemotactic gene that is also involved in other non-chemotactic functions due to the activity observed. D) Transcriptomics as a whole cannot be used for chemotaxis genes because they are not regulated at the transcriptional level (i.e., they are constitutive), which is why activity is observed on all three conditions.

Based on their abundance and location in bacterial genomes, deduce which is LEAST likely to horizontally transfer into another bacterium while maintaining its identical function and regulatory roles. A) heat shock protein-encoding gene B) lac operon C) catabolic regulon D) quorum sensing operon

In Bacteria, sensor kinases that respond to extracellular signals transfer this signal to the cytoplasmic machinery by typically phosphorylating the ________ residues. A) histidine B) serine C) threonine D) tyrosine

Which enzyme would be BEST to include in a protein extract to refold and denature improperly folded proteins? A) DnaK B) RepA C) RpoH D) Spo0A

Bacteria from the genus Caulobacter are used to model cellular differentiation in eukaryotes. The abundance of CtrA, DnaA, and GcrA separately control activity of other genes necessary for differentiation in Caulobacter. Thus, these three proteins can be classified as A) activating sensors. B) heterologous regulators. C) differentiating regulons. D) transcriptional regulators.

Which statement is TRUE of two separate regulators controlling one individual operon? A) The two regulators themselves must respond to different signals, which enables both to control the operon differently. B) One regulator will likely control the transcription of one section of the operon, whereas the other regulator will control the other component. C) One regulator will bind to the operator region whereas the other will bind to the promoter region so they can co-occur and co-regulate the operon. D) Two regulators trying to control the same operon will likely result in only one being maintained after several generations.

How would you design an sRNA to bind to a sequence? A) select six continuous nucleotides from the sequence B) take the complementary sequence of six continuous nucleotides C) select 200 continuous nucleotides from the sequence D) take the complementary sequence of 200 continuous nucleotides

Which of the following mechanisms leads to INCREASED transcriptional activity? A) An sRNA binds to the ribosome binding site. B) Ribonuclease activity is blocked by sRNA complementary binding to the end of a transcript. C) The ribosome binding site is made available from sRNA binding to part of it. D) Recruitment of RNA polymerase is enhanced when sRNA binds to and removes a repressor.

When the nontemplate strand of a gene is transcribed into RNA, what is likely to result? A) A complementary sRNA will bind to it and form a functional ribozyme with secondary structure. B) It will complementary bind to the gene sequence, form a hairpin loop, and transcriptionally repress the gene. C) The complementary mRNA also transcribed from the template strand will bind to it and halt its translation. D) A global regulator will identify this as a stress, respond by inducing ribonuclease production, and it will degraded.

How could you identify potential riboswitches with bioinformatics tools? A) Advanced 3D modeling techniques of mRNA folding would be necessary because complementary nucleotide binding predictions would not be useful. B) Locate short regions of an individual transcript with several complementary sites. C) Identify homologous sRNAs in other organisms. D) Identify several complementary mRNAs encoded in the genome.

Based on our understanding of the early stages of life, ________ is/are thought to be one of the earliest forms of metabolic regulation that evolved. A) attenuation B) feedback inhibition C) riboswitches D) transcription factors

Attenuation is a type of regulation that can control A) allosteric enzyme activity. B) transcriptional activity exclusively. C) translational activity exclusively. D) both transcriptional and translational activity.

Post-translational regulation of an enzyme's activity, such as glutamine synthetase, can be finely controlled at varied levels due to A) the varied strengths metabolite-regulating compounds can have with the enzyme such as hydrogen bonding, covalent bonding, and van der Waals attractions. B) having multiple independently functional subunits. C) the structural strength enzymes have once properly folded compared to short-lived and easily degradable transcripts during translational regulation. D) weak chemical modifications of the enzyme rather than harsh protein-protein or protein-DNA interactions.

Which of the following IS a characteristic of an isoenzyme? A) More than one enzyme is regulated by the same mechanism. B) The same reaction can be catalyzed by multiple enzyme variants. C) Multiple binding sites on the same enzyme enable multiple regulation mechanisms. D) More than one gene makes the same enzyme.

Which regulatory mechanism does NOT depend on a conformational change in protein/enzyme structure to change activity? A) attenuation B) catabolite repression C) feedback inhibition D) negative control

An organism grown in a high nutrient liquid broth to high turbidity always appears to produce a blue pigment and even when a large inoculum is transferred to a nutrient rich agar plate it appears blue. When the researcher noticed it never appears blue when very small colonies were grown in low nutrient agar plates. What is the most plausible conclusion? A) Large populations enabled the differentiation of a subpopulation of cells that created the blue pigment. B) Only high nutrient conditions provide enough energy for cells to produce this secondary metabolite that appears blue. C) The blue pigment production is linked to quorum sensing. D) The strong gradient from very high to low nutrient bioavailability induces production of the blue metabolite.

A bacterium that either partially or fully catabolizes an acyl-homoserine lactone will likely disrupt A) attenuation. B) chemotaxis. C) endospore formation. D) quorum sensing.

Phosphorylation of ________ regulates which direction a flagellum rotates, thus controlling whether an organism runs or tumbles. A) CheAW B) CheB C) CheY D) CheZ

What are the primary regulator units that control endospore formation? A) allosteric proteins B) antisense RNAs C) riboswitches D) sigma factors

During the biotransformation of a large molecular weight compound, two major products are formed. While one of the products is catabolized, the other compounds accumulation represses the biotransformation of the large compound. Which approach is MOST likely to artificially enhance the biotransformation beyond this point in a batch culture? A) addition of an isoenzyme for the biotransformation route to increase its transcription B) addition of inducer molecules into the medium to increase transcriptional repression C) inclusion of more of an intermediate compound in the catabolic pathway D) spike in additional activator proteins that control the transcription of this pathway

Quorum sensing generally follows the mechanism of which type of regulation? A) feedback inhibition B) negative transcriptional regulation C) positive transcriptional regulation D) two-component regulation system

What type of sRNA often requires a chaperon protein for strong regulation activity? A) antisense RNA B) riboswitches C) siRNA D) trans-sRNA

Which organism would likely harbor the MOST two-component regulatory systems? A) an archaeon living in an extreme environment B) a bacterium occupying a heterogeneous niche will high nutrient mixing C) an organism capable of quorum sensing D) a parasitic bacterium living inside another organism

How is the activity of a riboswitch controlled? A) by other riboswitches B) metabolite binding can change its structure C) sigma factor binding alters its structure D) small RNA complementary binding disrupts its function

Transcriptomics is a common approach to infer which metabolic pathways are actively functioning, but which regulation process can MOST significantly complicate or even abolish conclusions from this approach? A) activity of a catabolite repressor protein on multiple pathways B) antisense RNA silencing C) feedback inhibition with allosteric proteins D) presence of corepressors and inducers which are molecules undetected by transcriptomics