Kemp Biol 111 Chapter 19

If you already knew that the infectious agents was either bacterial or viral, which treatment would allow you to distinguish between two possibilities?

III

A researcher lyses a cell that cottons nucleic acid molecules and capsomeres of tobacco mosaic viruses (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 the typical symptoms of TMV infection

Which of the following describes plant virus infections?

They are spread throughout a plant by passing through the plasmodesmata

Which of the following is characteristic of the lytic cycle?

a large number of phages is released at a time

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 is an operon

emerging viruses arise by

all of the above

viral envelopes can best be analyzed with which of the following techniques?

antibodies against specific proteins not found in the host membranes

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

genetic material composed of nucleic acid

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

getting vaccinated

which of the following molecules make up the viral envelope?

glycoproteins

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome

Which of the following terms describes bacteriophage DNA that has become integrated into the host cell chromosome?

prophages

Most human-infecting viruses are maintained in the human population only. However, a zoonoshs is a disease that is transmitted from other vertebrates to humans, at least sporadically. Without requiring viral mutation. Which of the following is the best example of a zoonsis?

rabies

Given Baltimore's scheme, a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?

retroviruses that require a DNA intermediate

What characteristics of electron microscopes make them most useful for studying viruses?

shorter wavelengths providing higher resolution

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome?

size and shape of the capsid

the host range of a virus is determined by

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

Based on the above table, which virus meets the requirements for a bacteriophage?

A Dnase (-) (-)

Which of the following series 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 and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans

A linear piece of viral DNA of 8 kb can be cut with either of two restriction enzymes (X and Y). These are subjected to electrophoresis and produce the following bands. Cutting the same 8 kb piece with both enzymes together results in bands at 4.0, 2.5, 1.0 and .5. Of the possible arrangements of the sites given below, which one is most likely?

B Y- 2.75; X-3.25; Y-7.25

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

Certain environmental triggers can cause the phage to exit the host genome, switching form the hytic to the lysogenic

Based on the above table, which virus meets the Baltimore requirements for a retrovirus?

D Rnase (-) (+)

Which treatment could definitively determine whether or not the component is a viroid?

I

Which treatment would you use to determine if the agent is a prion?

IV only

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

Replication of their genomes does not involve pre proofreading steps of DNA replication

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

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?

The newly emerging virus will die out rather quickly or will mutate to be far less lethal

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 more similar to the genie of the host cell than to the genomes of viruses that infect other cell types

Which of the following is the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

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

become capable of human-to-human transmission

Which of the following accounts who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of life?

copies of the herpesvirus genome permanently maintained in host nuclei

Antiviral drugs that have become useful are usually associated with which of the following properties?

interference with the viral reproduction

What is the function of reverse transcriptase in retroviruses?

it uses viral RNA as a template for DNA synthesis

What are prions?

misfolded versions of normal brain protein

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?

retroviruses

why are viruses referred to as obligate parasites?

they cannot reproduce outside of a host cell

Which of the following represents a difference between viruses and viroids?

viruses infect many types of cells, whereas viroids infect only prokaryotic cells