Campbell Biology: Chap 19

retroviruses-What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

transcriptase -What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

bacteriophage-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.

bacterium-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.

viroids-What is a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

viruses-What is a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

plasmodesmata-What describes plant virus infections?

They are spread via the plasmodesmata.

bacteriophage-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, what would you expect of the genes of the bacteriophage?

control of more than one gene in an operon

capsid-Adenoviruses (I), influenza viruses (II), bacteriophage T4 (III) Which of the three types of viruses shown above would you expect to include a capsid(s)?

all three

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome.

bacteria-What characteristics, structures, or processes is common to both bacteria and viruses?

genetic material composed of nucleic acid

vaccinated-What can be effective in preventing the onset of viral infection in humans?

getting vaccinated

viral replication-Antiviral drugs that have become useful are usually associated with what properties?

interference with viral replication

viruses-Emerging viruses arise by

mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species.

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

rabies

retroviruses-What viruses have single-stranded RNA that acts as a template for DNA synthesis?

retroviruses

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

size and shape of the capsid

virus-The host range of a virus is determined by

the proteins on its surface and that of the host.

lytic cycle-What is characteristic of the lytic cycle?

A large number of phages are released at a time.

flu virus -What 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.

glycoproteins-Adenoviruses (I), influenza viruses (II), bacteriophage T4 (III) Which of the three types of viruses shown above would you expect to include glycoproteins?

I and II only

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

Replication of their genomes does not involve proofreading.

mortality-What 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.

lambda -What describes the lysogenic cycle of lambda (λ) phage?

The phage genome replicates along with the host genome.

lysogenic-What describes the lysogenic cycle of lambda (λ) phage?

The phage genome replicates along with the host genome.

TMV-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 do you expect to occur?

The plants would develop the typical symptoms of TMV infection.

Viral genomes-cellular nucleic acid-Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. What supports this theory?

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

cellular nucleic acid-Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. What supports this theory?

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

predictor -What is the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

Viral envelopes can best be analyzed with what techniques?

antibodies against specific proteins not found in the host membranes

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

become capable of human-to-human transmission.

herpesvirus-mediated cold sore-What 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?

copies of the herpesvirus genome permanently maintained in host nuclei

Antiviral drugs that have become useful are usually associated with what properties?

interference with viral replication

prions-What are prions?

misfolded versions of normal brain protein

Emerging viruses arise by

mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species.

horizontal transmission -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.

vertical transmission-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.