Chapter 15/17

Two potential devices that eukaryotic cells use to regulate transcription are histone amplification and DNA acetylation. DNA methylation and histone amplification. DNA acetylation and methylation. DNA amplification and histone methylation. DNA methylation and histone modification.

DNA methylation and histone modification

What is the function of reverse transcriptase in retroviruses? It uses viral RNA as a template for DNA synthesis. It uses viral RNA as a template for making complementary RNA strands. It translates viral RNA into proteins. It hydrolyzes the host cell's DNA. It converts host cell RNA into viral DNA.

It uses viral RNA as a template for DNA synthesis

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called RNA targeting. RNA interference. RNA blocking. RNA disposal. RNA obstruction.

RNA interference

Which one of the following techniques involves reverse transcriptase, PCR amplification, and gel electrophoresis? RT-PCR RNA interference DNA microarray assays nucleic acid hybridization in situ hybridization

RT-PCR

Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the repressor gene (lac I), along with its promoter, to a position some several thousand base pairs away from its normal position, which will you expect to occur? The repressor will no longer be made. The repressor will no longer bind to the operator. The repressor will no longer bind to the inducer. The lac operon will be expressed continuously. The lac operon will function normally.

The lac operon will function normally

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur? The plants would develop some but not all of the symptoms of the TMV infection. The plants would not show any disease symptoms. The plants would become infected, but the sap from these plants would be unable to infect other plants. The plants would develop symptoms typically produced by viroids. The plants would develop the typical symptoms of TMV infection.

The plants would develop the typical symptoms of TMV infection

Which of the following describes plant virus infections? They are seldom spread by insects. They have little effect on plant growth. They are spread via the plasmodesmata. They can be controlled by the use of antibiotics. They can never be passed vertically.

They are spread via the plasmodesmata

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in irreversible binding of the repressor to the operator. continuous transcription of the structural gene controlled by that regulator. complete inhibition of transcription of the structural gene controlled by that regulator. inactivation of RNA polymerase by alteration of its active site. continuous translation of the mRNA because of alteration of its structure.

continuous transcription of the structural gene controlled by that regulator

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage? regulation via acetylation of histones positive control mechanisms rather than negative control of more than one gene in an operon utilization of eukaryotic polymerases reliance on transcription activators

control of more than one gene in an operon

https://session.masteringbiology.com/problemAsset/1673619/1/3153517001.jpg Which of the three types of viruses shown in the figure would you expect to include a capsid(s)? I and II only II only III only I only all three

all three

DNA microarrays have had a huge impact on genomic studies because they allow the expression of many or even all of the genes in a genome to be compared at once. can identify the function of any gene in a genome. dramatically enhance the efficiency of restriction enzymes (endonucleases). can be used to introduce entire genomes into bacterial cells. allow physical maps of the genome to be assembled in a very short time.

allow the expression of many or even all of the genes in a genome to be compared at once

Viral envelopes can best be analyzed with which of the following techniques? use of plaque assays for quantitative measurement of viral titer antibodies against specific proteins not found in the host membranes immunofluorescent tagging of capsid proteins DNA staining and visualization with the light microscope use of 15N to label specific nucleotides

antibodies against specific proteins not found in the host membranes

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see? increased chromatin condensation decreased chromatin condensation activation of histone tails for enzymatic function decreased binding of transcription factors inactivation of the selected genes

decreased chromatin condensation

In a genome-wide expression study using a DNA microarray assay, each well is used to detect the location of a gene within a cell. type of chemical modification of proteins produced by a cell. fate of proteins produced by a cell. location of a protein produced by a cell. expression of a specific gene by a cell.

expression of a specific gene by a cell

Which of the following characteristics, structures, or processes is common to both bacteria and viruses? cell division genetic material composed of nucleic acid independent existence metabolism ribosomes

genetic material composed of nucleic acid

Which of the following can be effective in preventing the onset of viral infection in humans? taking nucleoside analogs that inhibit transcription taking vitamins taking antibiotics getting vaccinated applying antiseptics

getting vaccinated

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator? corepressor inducer repressor ubiquitin promoter

inducer

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity? accessibility of heterochromatin to phosphorylating enzymes nucleotide excision and reconstruction methylation and phosphorylation of histone tails hydrolysis of DNA molecules where they are wrapped around the nucleosome core DNA supercoiling at or around H1

methylation and phosphorylation of histone tails

Which of the following is a protein produced by a regulatory gene? repressor corepressor promoter operon inducer

repressor

Which of the following is an example of post-transcriptional control of gene expression? the addition of methyl groups to cytosine bases of DNA the binding of RNA polymerase to transcription factors the binding of transcription factors to a promoter the removal of introns and alternative splicing of exons the folding of DNA to form heterochromatin

the removal of introns and alternative splicing of exons

The functioning of enhancers is an example of a post-transcriptional mechanism to regulate mRNA. a eukaryotic equivalent of prokaryotic promoter functioning. post-translational control that activates certain proteins. transcriptional control of gene expression. the stimulation of translation by initiation factors.

transcriptional control of gene expression

Use the following information to answer the following question. In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. the table shows the results of testing five viruses (AE) for nuclease specificity, the ability of the viral genome to act as an mRNA, and the presence (+) or absence () of each viruss own polymerase. https://session.masteringbiology.com/problemAsset/1673623/1/3153517003.jpg Based on the table, which virus meets the requirements for a bacteriophage? A B C D E

A

Which of the following is characteristic of the lytic cycle? Many bacterial cells containing viral DNA are produced. The viral genome replicates without destroying the host. The virus-host relationship usually lasts for generations. Viral DNA is incorporated into the host genome. A large number of phages are released at a time

A large number of phages are released at a time

Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells? A single repressor is able to turn off several related genes. The genes are organized into large operons, allowing them to be transcribed as a single unit. Environmental signals enter the cell and bind directly to promoters. The genes share a single common enhancer, which allows appropriate activators to turn on their transcription at the same time. A specific combination of control elements in each genes enhancer coordinates the simultaneous activation of the genes.

A specific combination of control elements in each genes enhancer coordinates the simultaneous activation of the genes

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? The repressor protein attaches to the regulator. RNA polymerase attaches to the regulator. Allolactose binds to the repressor protein. Allolactose binds to the regulator gene. The repressor protein and allolactose bind to RNA polymerase.

Allolactose binds to the repressor protein

Based on the table, which virus meets the Baltimore requirements for a retrovirus? https://session.masteringbiology.com/problemAsset/1673622/1/3153517003.jpg

D

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained? As RNAs have evolved since that time, they have taken on new functions. Ethical considerations prevented scientists from exploring this material until recently. Watson and Crick described DNA but did not predict any function for RNA. Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible. The functions of small RNAs could not be approached until the entire human genome was sequenced.

Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible

https://session.masteringbiology.com/problemAsset/1673618/1/3153517001.jpg Which of the three types of viruses shown in the figure would you expect to include glycoproteins? I only I and II only III only II only all three

I and II only

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant? It cannot bind to the inducer. It cannot make a functional repressor. It cannot bind to the operator. It makes molecules that bind to one another. It makes a repressor that binds CAP.

It cannot bind to the inducer

Which of the following statements about the DNA in one of your brain cells is true? It is the same as the DNA in one of your kidney cells. The majority of genes are likely to be transcribed. Many genes are grouped into operon-like clusters. Each gene lies immediately adjacent to an enhancer. Most of the DNA codes for protein.

It is the same as the DNA in one of your kidney cells

Why do RNA viruses appear to have higher rates of mutation? RNA viruses can incorporate a variety of nonstandard bases. RNA nucleotides are more unstable than DNA nucleotides. RNA viruses are more sensitive to mutagens. RNA viruses replicate faster. Replication of their genomes does not involve proofreading.

Replication of their genomes does not involve proofreading

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line? The transgene integrated into a euchromatic region of the genome. The host cell lacks the enzymes necessary to express the transgene. The transgene integrated into a heterochromatic region of the genome. The transgene integrated into a region of the genome characterized by high histone acetylation. The transgene was mutated during the process of integration into the host cell genome.

The transgene integrated into a heterochromatic region of the genome

Use the following information to answer the few questions. The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations? Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage. The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate. The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus. The viral envelope is not required for infectivity, since the envelope does not enter the nucleus.

The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus.

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory? Viral genomes are usually similar to the genome of the host cell. Viruses can infect both prokaryotic and eukaryotic cells. Viruses are enclosed in protein capsids rather than plasma membranes. Viruses can reproduce only inside host cells. Viruses contain either DNA or RNA.

Viral genomes are usually similar to the genome of the host cell

Which of the following is the best predictor of how much damage a virus causes? whether the infected cell produces viral protein how much toxin the virus produces ability of the infected cell to carry on translation whether the viral mRNA can be transcribed ability of the infected cell to undergo normal cell division

ability of the infected cell to undergo normal cell division

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways? allowing environmental changes to alter the prokaryote's genome allowing the organism to adjust to changes in environmental conditions allowing young organisms to respond differently from more mature organisms allowing each gene to be expressed an equal number of times organizing gene expression so that genes are expressed in a given order

allowing the organism to adjust to changes in environmental conditions

In response to chemical signals, prokaryotes can do which of the following? alter the sequence of amino acids in certain proteins turn off translation of their mRNA increase the number and responsiveness of their ribosomes inactivate their mRNA molecules alter the level of production of various enzymes

alter the level of production of various enzymes

A human pandemic is a flu that kills more than 1 million people. a viral disease that can infect multiple species. a virus that increases in mortality rate as it spreads. an epidemic that extends around the world. a viral disease that infects all humans.

an epidemic that extends around the world

In eukaryotes, general transcription factors inhibit RNA polymerase binding to the promoter and begin transcribing. bind to sequences just after the start site of transcription. bind to other proteins or to a sequence element within the promoter called the TATA box. are required for the expression of specific protein-encoding genes. usually lead to a high level of transcription even without additional specific transcription factors.

bind to other proteins or to a sequence element within the promoter called the TATA box

The role of a metabolite that controls a repressible operon is to bind to the operator region and block the attachment of RNA polymerase to the promoter. bind to the repressor protein and activate it. bind to the promoter region and decrease the affinity of RNA polymerase for the promoter. increase the production of inactive repressor proteins. bind to the repressor protein and inactivate it.

bind to the repressor protein and activate it

Steroid hormones produce their effects in cells by activating key enzymes in metabolic pathways. activating translation of certain mRNAs. promoting the formation of looped domains in certain regions of DNA. binding to intracellular receptors and promoting transcription of specific genes. promoting the degradation of specific mRNAs.

binding to intracellular receptors and promoting transcription of specific genes

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life? re-infection by the same herpesvirus strain copies of the herpesvirus genome permanently maintained in host nuclei co-infection with an unrelated virus that causes the same symptoms re-infection by a closely related herpesvirus of a different strain copies of the herpesvirus genome permanently maintained in host cell cytoplasm

copies of the herpesvirus genome permanently maintained in host nuclei

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see? increased chromatin condensation decreased chromatin condensation activation of histone tails for enzymatic function decreased binding of transcription factors inactivation of the selected genes

decreased chromatin condensation

Use the following information to answer the few questions. The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection? medication that destroys surface HSV before it gets to neurons education about avoiding sources of infection interference with new viral replication in preexisting cases vaccination of all persons with preexisting cases treatment of the HSV lesions to shorten the breakout

interference with new viral replication in preexisting cases

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for most of the rest? non-protein-coding DNA that is transcribed into several kinds of small RNAs without biological function non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function "junk" DNA that serves no possible purpose rRNA and tRNA coding sequences DNA that is translated directly without being transcribed

non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

In the figure, when new viruses are being assembled (IV), what mediates the assembly? nothing; they self-assemble assembly proteins coded for by the viral genes assembly proteins coded for by the host nucleus viral RNA intermediates host cell chaperones

nothing; they self-assemble

Transcription of the structural genes in an inducible operon occurs continuously in the cell. starts when the pathway's product is present. starts when the pathway's substrate is present. stops when the pathway's product is present. does not result in the production of enzymes.

starts when the pathway's substrate is present

The lactose operon is likely to be transcribed when there is more glucose in the cell than lactose. the cyclic AMP levels are low. the cyclic AMP and lactose levels are both high within the cell. the cAMP level is high and the lactose level is low. there is glucose but no lactose in the cell.

the cyclic AMP and lactose levels are both high within the cell

The host range of a virus is determined by the proteins in the host's cytoplasm. the enzymes carried by the virus. the proteins on its surface and that of the host. the enzymes produced by the virus before it infects the cell. whether its nucleic acid is DNA or RNA.

the proteins on its surface and that of the host

The difference between vertical and horizontal transmission of plant viruses is that vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species. vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. vertical transmission is the spread of viruses from the upper leaves to the lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.

vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant