Biology Chapter 19 & 20 Review

Which of the following human diseases is caused by a virus that requires reverse transcriptase to transcribe its genome inside the host cell?

AIDS

Which of the following problems with animal cloning might result in premature death of the clones?

Abnormal gene regulation due to variant methylation.

Which of the following processes helps bacterial cells protect their own DNA from restriction enzymes (endonucleases)?

Adding methyl groups to adenines and cytosines.

Emerging viruses arise by

All of the above.

In DNA technology, the term vector can refer to

A plasmid used to transfer DNA into a living cell.

Why is sequencing an entire genome, such as that of C. elegans, a nematode, important for genetic research?

A sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

Plants are more readily manipulated by genetic engineering than are animals because

A somatic plant cell can often give rise to a complete plant.

Which of the following statements best reflects what we know about how the flu virus moves between species?

An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans.

What is difference between an epidemic and a pandemic?

An epidemic is restricted to a local region: a pandemic is global

A population of viruses with similar characteristics is called a

Class.

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning, there is a wider divergence of opinion. Which of the following statements provides a likely explanation?

Cloning to produce embryonic stem cells may lead to great medical benefits for many.

Many identical copies of genes cloned in bacteria are produced as a result of which of the following processes?

Plasmid and bacterial cell reproduction.

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

Which of the following is not true of cDNA produced using human brain tissue as the starting material?

It was produced from pre-mRNA using reverse transcriptase.

DNA technology has many medical applications. Which of the following is not done routinely at present?

Gene editing by the CRISPR-Cas9 system in viable human embryos to correct genetic diseases.

Which of the following processes can be effective in preventing the onset of viral infection in humans?

Getting vaccinated to certain viruses.

Which of the three types of viruses shown would you expect to include glycoproteins?

II only.

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following safety measures is one that has been adopted by researchers?

Microorganisms used in recombinant DNA experiments must be genetically crippled to ensure that they cannot survive outside of the laboratory.

What are prions?

Misfolded versions of normal proteins that can cause disease.

Why might using retroviral vectors for gene therapy increase the patient's risk of developing cancer?

Retroviral vectors integrate recombinant DNA into the genome in ways that may misregulate the expression of genes at or near the site of integration.

A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a

Retrovirus.

Which of the following enzymes is required to make complementary DNA (cDNA) from RNA?

Reverse transcriptase.

In large scale, genome-wide association studies in humans, what types of genetic markers do researchers look for?

SNPs where one allele is found more often in persons with a particular disorder than in healthy controls.

Which of the following statements correctly describes how RNA interference (RNAi) silences selected genes?

Synthetic double-stranded RNA molecules trigger the breakdown of a gene's messenger RNA.

What information is critical to the success of polymerase chain reaction (PCR) itself?

The DNA sequence of ends of the DNA to be amplified must be known.

A person is most likely to recover from a cold due to viral infection if the infected cells are able to perform which of the following processes?

The cells can undergo normal cell division.

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following findings is likely from this comparison?

The cells from the two sources exhibit different patterns of DNA methylation.

The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?

The lytic cycle only.

Which of the following statements accurately describes the lysogenic cycle of lambda phage?

The phage genome is integrated in the host where it is replicated along with the host genome.

Which of the following statements correctly describes vaccines and how they help prevent viral infection?

Vaccines are inactive versions of a virus that stimulate an immune reaction in a person.

Which of the following descriptions correctly identifies the main structural differences between viruses with envelopes and viruses without envelopes?

Viruses with envelopes have a phospholipid membrane outside their capsid, whereas viruses without envelopes do not have a phospholipid membrane.

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why was this the case with this clone?

X chromosome inactivation in the embryo is random and produces different patterns.

Evidence suggests that factors that contribute towards the virulence of E. coli strain O157:H7, a bacterial strain reported to cause several food poisoning deaths, are caused by genes from a virus that infects bacteria. Considering this evidence, which of the following statements most likely explains how the O157:H7 population acquired the genetic variation that distinguishes the strain from harmless E. coli strains, such as those that reside in our intestines?

The virus infected the bacterium, and allowed the bacterial population to replicate with a copy of the phage genome in each new bacterium.

Which of the following statements is correct regarding viral infections in plants?

They can spread within a plant via plasmodesmata.

Which of the following processes can viruses carry out?

They can use the host cell to copy themselves and make viral proteins.

How can a gene that contains introns be made shorter (but remain functional) for genetic engineering purposes?

Using reverse transcriptase to reconstruct the gene from its mRNA.

Which of the following statements describes one of the technical reasons why gene therapy is problematic in humans?

Transferred genes may not have appropriately controlled activity.

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. Which of the following types of evidence will researchers be looking for in order to determine if the cells are cancerous?

a pattern shared by some or all of the samples that indicates gene expression differing from control samples.

One possible use of transgenic plants is in the production of human proteins, such as vaccines. Which of the following issues is a possible hindrance that must be overcome in order for this process to work properly?

prevention of transmission of plant allergens to the vaccine recipients.

Cells were infected with approximately 1,000 copies of either virus A or virus B at the 0 time point. At five-minute intervals, a sample of the virus and cell mixture was removed. The intact cells were removed from the sample, and the number of viruses per milliliter of culture was determined. Using the data in the figure, how long does it take for virus A to go through one lytic cycle?

45 minutes

Which of the following sequences is most likely to be cut by a restriction enzyme?

5′-AATATT-3′ 3′-TTATAA-5′

Cells were infected with approximately 1,000 copies of either virus A or virus B at the 0 time point. At five-minute intervals, a sample of the virus and cell mixture was removed. The intact cells were removed from the sample, and the number of viruses per milliliter of culture was determined. Using the data in the figure, how long does it take for virus B to go through one lytic cycle?

60 minutes

Why is it so important to be able to amplify DNA fragments when studying genes?

A gene may represent only a millionth of the cell's DNA.

Which of the following characteristics is typical of the lytic cycle of a bacteriophage?

A large number of phages are released at a time.

Which of the following enzymes was used to produce the molecule of DNA in the figure?

A restriction enzyme (endonuclease).

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). To make this conversion, what has been done to the adult cells?

A retrovirus is used to introduce four specific master regulatory genes.

Which of the following viruses would most likely have reverse transcriptase inside them?

An RNA-based lysogenic virus.

A principal problem with inserting an unmodified mammalian gene into a plasmid and then getting that gene expressed in bacteria is that

Bacteria cannot remove eukaryotic introns.

In the form of gene therapy used successfully for severe combined immunodeficiency syndrome, SCID-X1, how is the genetic engineering of human cells achieved?

By isolating the patient's bone marrow cells, infecting them with genetically engineered viruses, and injecting them back into the patient's bone marrow.

The segment of DNA shown in the figure above has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments?

C A B

Transgenic mice are useful to human researchers because they

Can be valuable animal models of human disease.

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?

Control of more than one gene in an operon.

Which of the following events or characteristics accounts for someone who has had regular herpes virus-mediated cold sores or genital sore flare ups?

Copies of the herpes virus genome permanently maintain in host nuclei.

What is the most favorable characteristic of retroviruses that makes them useful in gene therapy applications?

DNA copies of retroviral genomes become integrated into the genome of the infected cell.

Which of the following tools of DNA technology is incorrectly paired with its use?

DNA-ligase: cutting DNA, creating sticky ends of restriction fragments.

Which of the following methods would be most successful in attempting to introduce a particular piece of DNA into an animal cell?

Electroportation followed by recombination.

Which of the following statements correctly describes one of the main differences between embryonic stem cells and adult stem cells?

Embryonic stem cells can give rise to all cell types in the organism, and adult stem cells cannot.

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?

GGCC CCGG

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

Genetic material composed of nucleic acid.

One predicted aspect of climate change is that climates, including precipitation and temperature, over most of Earth will become more variable. Which of the following is a good strategy for genetically engineering crops if this is true?

Genetically engineer several genotypes within single crop types.

Why do scientists consider HIV to be an emerging virus?

HIV suddenly became apparent and widespread in the 1980s.

Which of the following processes within viral replication is the greatest source of genetic variation in RNA virus populations?

High mutation rate due to lack of proofreading of RNA genome replication errors.

In the figure, at the arrow marked II, what enzyme is being utilized?

Host cell DNA polymerase

RNA viruses require their own supply of certain enzymes because

Host cells lack enzymes that can replicate the viral genome.

You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, or prion. You have four methods at your disposal to analyze the substance and determine the nature of the infectious agent. I. Treat the substance with enzymes that destroy all nucleic acids, and then determine whether the substance is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance on nutritive medium, away from any plant cells. IV. Treat the sample with proteases that digest all proteins, and then determine whether the substance is still infectious. If you already know that the infectious agent was either a virus or a prion, which method(s) listed above would allow you to distinguish between these two possibilities?

I only

Suppose that a researcher is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still pose problems for this individual? I. the possibility that, once introduced into the patient, the iPS cells produce non-pancreatic cells II. the failure of the iPS cells to take up residence in the pancreas III. the inability of the iPS cells to respond to appropriate regulatory signals

I, II, and III

Which of the three types of viruses shown in the figure would you expect to include a capsid(s)?

I, II, and III.

You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, or prion. You have four methods at your disposal to analyze the substance and determine the nature of the infectious agent. I. Treat the substance with enzymes that destroy all nucleic acids, and then determine whether the substance is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance on nutritive medium, away from any plant cells. IV.Treat the sample with proteases that digest all proteins, and then determine whether the substance is still infectious. If you already know that the infectious agent was either bacterial or viral, which method(s) listed above would allow you to distinguish between these two possibilities?

II or III

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes (endonucleases). III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to non-plasmid DNA fragments. V. Use ligase to seal plasmid DNA to non-plasmid DNA.

III, II, IV, V, I

The herpes viruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms 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 later reactivate, replicate again, and infect others. If scientists are trying to use what they know about the herpes simplex virus to devise a means of protecting other people from being infected, which of the following treatments would have the best chance of lowering the number of new cases of infection?

Interfere with new viral replication in preexisting cases of herpes simplex virus.

Effective antiviral drugs are usually associated with which of the following properties?

Interference with viral replication.

Which of the following characteristics of Taq polymerase make it useful in the PCR process?

It is heat stable and can withstand the heating step of PCR.

The final step in a Sanger DNA sequencing reaction is to run the DNA fragments on a gel. What purpose does this serve?

It separates DNA fragments generated during the sequencing reaction based on one-nucleotide differences in their size.

In the figure, when new viruses are being assembled at the point marked IV, what mediates the assembly?

No mediator is required; the new viruses self assemble

Will treating a viral infection with antibiotics affect the course of the infection?

No; antibiotics work by inhibiting enzymes specific to bacteria. Antibiotics have no effect on eukaryotic or virally encoded enzymes.

Organisms share many conserved core processes and features, including transcription and translation, using a uniform genetic code. Scientists have used these shared processes and features in biotechnology. For example, for the process of some transformations, a plasmid is constructed when a eukaryotic gene of interest is added with an antibiotic resistant gene such as beta-lactamase, which is used for ampicillin resistance. This plasmid is then inserted into a prokaryotic bacterial cell, such as E. coli, through a transformation process that leads to the production of the product protein from the eukaryotic organism. To culture the bacteria and obtain the protein product, the bacteria must grow. Select the appropriate condition to determine if the plasmid has entered the E. coli bacterial cell.

Nutrient broth to which ampicillin has been added.

Which of the following processes is most like the formation of identical twins?

Organismal cloning.

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is also found in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following characteristics of this gene?

Pax-6 is highly conserved and shows evolutionary ancestry.

A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). To compare a specific region of the DNA from a sample with DNA from living birds, which of the following would be most useful for increasing the amount of dodo DNA available for testing?

Polymerase chain reaction (PCR).

Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of

Post-transcriptional processing.

In 2009, a flu pandemic was believed to have originated when viral transmission occurred from pig to human, thereby earning the designation "swine flu." Although pigs are thought to have been the breeding ground for the 2009 virus, sequences from bird, pig, and human viruses were all found within this newly identified virus. What is the most likely explanation of why this virus contained sequences from bird, pig, and human viruses?

Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly.

Why do RNA viruses appear to have higher rates of mutation?

Replication of their genomes does not involve proofreading.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

T4 protein and T4 DNA.

Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its 5′ end, the RNA genome has a viral protein (VPg) instead of a 5′ cap. This is followed by a non- translated leader sequence, and then a single long protein-coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acids similar in structure to those that are found in viruses and other organisms. Short-period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment?

The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.

Which of the following information or processes does gene therapy require?

The ability to introduce the normal allele into the patient.

The first class of antiviral drugs developed to treat HIV infection, such as AZT, were known as reverse transcriptase inhibitors. How did these drugs carry out their functions?

The drug molecules bonded to the viral reverse transcriptase enzyme, thus preventing the virus from making a DNA copy of its RNA genome.

23) HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings?

The flu virus can be transmitted more easily from person to person than HIV.

The host range of a virus is determined by

The proteins on its surface and that of the host

Which of the following characteristics of short tandem repeats (STRs) DNA makes it useful for DNA fingerprinting?

The number of repeats is highly variable from person to person or animal to animal.

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. What would you expect to happen to the plants that were sprayed with the mixture?

The plants would develop the typical symptoms of the TMV infection.

22) If a viral host cell has a mutation that interferes with the addition of carbohydrates to proteins in the Golgi apparatus, which of the following processes could likely result?

The viral envelope proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane.

The herpesviruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms 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 later reactivate, replicate again, and infect 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 statements best fits these observations?

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

Viruses use the host cell's machinery to make copies of themselves. However, some human viruses require a type of replication that humans do not normally have. For example, humans normally do not have the ability to convert RNA into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?

The viral genome codes for specialized enzymes not found in the host cells.

In animals, what is the difference between reproductive cloning and therapeutic cloning?

Therapeutic cloning supplies cells for repair of diseased or injured organs.

How have DNA microarrays made a huge impact on genomic studies?

They allow the expression of many or all of the genes in the genome to be compared at once.

Why are yeast cells frequently used as hosts for cloning?

They are eukaryotic cells.

In a comparison of two DNA sequences found in the same location on homologous chromosomes, one of the homologs carries the sequence 5′-AACTACGA-3′, and the other homolog carries the sequence 5′-AACTTCGA-3′. Within a population, you discover that each of these sequences is common. Which of the following statements correctly describes theses sequences?

They contain a SNP that may be useful for genetic mapping.

Which of the following statements supports the argument that viruses are nonliving?

They do not carry out metabolic processes.

Which of the following characteristics correctly describes retroviruses?

They have a single-stranded RNA that acts as a template for DNA synthesis.

Which of the following statements correctly describes one characteristic of genetically engineered plants?

They include transgenic rice plants that can grow in water more salty than seawater.

RNAi methodology uses double-stranded pieces of RNA to trigger breakdown of a specific mRNA or inhibit its translation. For which of the following processes might this technique be useful?

To decrease the production from a harmful mutated gene.

For which of the following processes can dideoxyribonucleotides be used?

To sequence a DNA fragment.

In 1997, Dolly the sheep was cloned. Which of the following processes was used?

Transfer of an adult cell's nucleus into an enucleated sheep egg, followed by incubation in a surrogate.

Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6,300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure when analyzing the reproduction of this virus?

Translation rate.

The difference between vertical and horizontal transmission of plant viruses is that 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.

Which of the following statements correctly describes a difference between viruses and prions?

Viruses generally cause disease symptoms quickly, whereas prions generally take many years to cause disease symptoms.

Select an observation that best describes a correct aspect of the two processes of restriction digest and gel electrophoresis.

When separated on a gel, the pattern of DNA bands will be characteristic of those cut with Hind III; different restriction enzymes will not produce these same fragments.

To cause a human pandemic, the H5N1 avian flu virus would have to

become capable of human-to-human transmission.

Which of the following correctly lists the processes in order for one cycle of polymerase chain reaction (PCR)?

denature DNA; anneal primers; extend primers

Which of the following processes uses labeled probes to visualize the expression of genes in whole tissues and organisms?

in situ hybridization.

Which of the following types of viral genomes could be transcribed using reverse transcriptase?

ssRNA.