Mastering Micro Exam 2

When is the repressor protein transcribed? It is always transcribed. Only in the absence of tryptophan Only in the presence of tryptophan

It is always transcribed

The field of study that can reveal how genes function, reveal how organisms interact with the environment, and show evolutionary relationships is __________. genomics transcriptomics proteomics comparative genomics

comparative genomics

Comparing the different generations of DNA sequencing, which would be most appropriate for a 10 Mbp piece of DNA that could not be fragmented? second generation third generation fourth generation first generation

fourth generation

Using quorum sensing, how do bacteria know when there are sufficient numbers present to express a specific gene? A high concentration of autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer in the cell triggers the two-component system to turn on transcription of the specific gene. A low concentration of an autoinducer outside the cell triggers the two-component system to turn on transcription of the specific gene. A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene.

A high concentration of autoinducer inside the cell triggers the two-component system to turn on transcription of the specific gene.

What structure can the viral genome take? ds-RNA ss-DNA ds-DNA All of the listed responses are correct

All of the listed responses are correct

In which stage does formation of mature viruses occur? Attachment Assembly Biosynthesis Release Penetration

Assembly

The host DNA is usually degraded during which stage? Assembly Penetration Biosynthesis Attachment Release

Biosynthesis

Which operons are never transcribed unless activated? Inducible operons Repressible operons Inducible and repressible operons

Inducible operons

In which stage is the viral DNA introduced into the cell? Release Biosynthesis Assembly Penetration Attachment

Penetration

Why does the structure of plant and bacterial cells illustrate the reason for having few enveloped viruses that infect these cells? Plant and bacterial cells contain cell walls that prevent viral infection. Plant and bacterial cells contain cell walls that prevent viruses from being released from the cell. Plant and bacterial cells contain cell walls that prevent attachment of viruses. Plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope.

Plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope.

Which of the following genetic elements is transcribed into a single mRNA? The operator The repressor The inducer The structural genes The promoter

The structural genes

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? The virus would not be able to infect new hosts. The cell could still be revived by the virus. The virus would infect new hosts.

The virus would not be able to infect new hosts.

Why is the tryptophan operon turned off in the presence of tryptophan? Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription. Tryptophan is not an important amino acid for cells. Tryptophan can be used over and over again in the cell.

Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

Which of the following is NOT a way in which viruses are different from living organisms? Viruses are obligate parasites and no living organisms are obligate parasites. Viruses have DNA or RNA, not both Viruses depend on their host to synthesize the essential components of new viruses (e.g., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities. Viruses are acellular and all living things are made up of cells

Viruses are obligate parasites and no living organisms are obligate parasites.

One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant? Hints a mutation that disables the repressor a mutation in the gene for beta-galactosidase permease a mutation that disables the promoter for the operon a mutation in the gene for beta-galactosidase

a mutation that disables the repressor

What is the inducer molecule in the lac operon? Repressor proteins Allolactose Glucose Lactose Galactose

allolactose

According to the animation, how do the repressor proteins block the transcription of the structural genes? It binds to the promoter when deactivated. It binds to the repressor when deactivated. It binds to the operator when activated. It binds to the repressor gene when activated. It binds to the promoter when activated. It binds to the repressor gene when deactivated.

It binds to the operator when activated.

When the cell is NOT in the presence of tryptophan, RNA polymerase can transcribe mRNA. the repressor proteins bind to the operator. the repressor proteins are active. structural genes are not transcribed.

RNA polymerase can transcribe mRNA.

Which operons are always transcribed unless deactivated? Inducible operons Repressible operons Inducible and repressible operons

Repressible operons

Researchers discover a new species of bacterium that has an unusual metabolism. However, it has biochemical and morphological similarities to other species. What is the most comprehensive and effective approach to determine how to classify these bacteria? The bacteria should be classified with the other bacteria that use the most similar biochemical pathways. Because of their unusual metabolic pathways, the bacteria should be classified in a new group. The bacteria should be classified with other bacteria that have the most similar morphology. The bacteria should be classified by using genomic analyses to construct phylogenies.

The bacteria should be classified by using genomic analyses to construct phylogenies.

Two-component regulatory systems rely on a balance of phosphorylation and dephosphorylation of sensor kinases and response regulators. If the response regulator became permanently phosphorylated due to lack of phosphatase activity, which of the following would NOT happen? The cell would become more sensitive to the environmental stimulus. The cell would become insensitive to the environmental stimulus. The cell would not be able to "reset" its response cycle. The operon controlled by the response regulator would be always transcribed or never transcribed, depending upon the regulatory role of the response regulator.

The cell would become more sensitive to the environmental stimulus.

What would be the most likely effect of a mutation in the operator of a lac operon? The genes would be constitutively expressed. beta-galactosidase would not be produced. Regulation would occur normally. The repressor would not be produced.

The genes would be constitutively expressed.

According to the animation, where on the DNA strand does a repressor bind? The operator The inducer The promoter The structural genes

The operator

With which genetic region does the repressor protein interact? lacZ lacY The operator region The regulatory gene The promoter region

The operator region

What is the basic function of the lac operon? To code for enzymes involved in catabolizing lactose. To produce lactose when none is present To code for enzymes involved in synthesizing lactose. To produce glucose when none is available

To code for enzymes involved in catabolizing lactose.

What is the overall function of the trp operon? To ensure that the cell has a supply of tryptophan at all times To control the production of repressor proteins To block RNA polymerase from the structural genes To always make sure the operator is being bound to repressor proteins

To ensure that the cell has a supply of tryptophan at all times

What component(s) make up the structure of a virion? capsid and genome genome and envelope capsid, genome, envelope capsid

capsid and genome

Which of the following is NOT included in the genome? noncoding regions of DNA proteins genes that encode RNAs coding regions of DNA

proteins

Gene duplication is thought to have had a significant influence on the evolution of microbes because __________. the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original (and possibly essential) genetic function the duplicated gene can allow for increased transcription and synthesis of the gene product the duplicated gene can serve as a "back-up" copy the duplicated gene can be given away to another organism by conjugation

the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original (and possibly essential) genetic function

Horizontal gene transfer refers to the transfer of genes from one organism to another, as occurs during conjugation between bacteria. How does this differ from vertical gene transfer? In horizontal gene transfer, genes are transferred from one mature adult organism to another. In vertical gene transfer, genes are transferred from adults to offspring. Conjugation can involve horizontal or vertical gene transfer, depending on the physical orientation of the bacteria involved. In vertical gene transfer, genes are transferred by a vector such as a bacteriophage. In horizontal gene transfer, genes are transferred between two organisms of the same species. In vertical gene transfer, genes are transferred between two organisms of different species.

In horizontal gene transfer, genes are transferred from one mature adult organism to another. In vertical gene transfer, genes are transferred from adults to offspring.

In the lac operon, which of the following conditions would allow the structural genes to be transcribed? Hints Glucose is present and lactose is absent. Lactose and glucose are present. Lactose and glucose are absent. Lactose is present and glucose is absent.

Lactose is present and glucose is absent.

The genome sequence of an organism can provide information about the organism's __________. function, size, and evolutionary history genes, size, and function function, evolutionary history, and morphology genes, function, and evolutionary history

genes, function, and evolutionary history

If a researcher wanted to compare the enzymatic capacity to degrade compounds in a water column at various depths under a specific set of conditions, which would be the most useful approach? metaproteomics metagenomics metabolomics genomics

metaproteomics

Sequencing an organism's genome often leads to identification of hypothetical proteins, which are characterized as __________. proteins that are overexpressed proteins that are expressed proteins that likely exist though their function is unknown proteins that likely exist with known functions

proteins that likely exist though their function is unknown

According to the animation, to what genetic element does the RNA polymerase bind? The repressor protein The repressor mRNA The operator The promoter

the promoter

When the cell is not in the presence of lactose, the repressor proteins are inactivated. the repressor proteins bind to the operator. transcription of the structural genes occurs. no transcription of the regulatory genes occurs.

the repressor proteins bind to the operator.