Micro Chapter 6 Test – Flashcards

Viruses have typical cellular structure like other living organisms. T/F

Viruses in the extracellular state possess few, if any, active enzymes. T/F

Which is not true of viruses?

Which of the following is true of viruses in the extracellular phase?

A complete virus particle is called a

The nucleic acids carried by viruses usually consist of

Which of the following is not true of viruses?

Viruses infecting protists, including algae, have never been detected. T/F

One way in which small viruses package more information into a very small genome is to use overlapping genes so that the same base sequence is read in more than one reading frame. T/F

Almost all known plant viruses are RNA viruses. T/F

Virus morphology does not include which of the following characteristics?

__________ are glycoprotein spikes protruding from the outer surface of the viral envelope.

Icosahedral viruses are constructed from ring- or knob-shaped units called __________.

Viruses that are polyhedrons with 20 sides are said to have __________ symmetry.

The most common capsid morphologies are icosahedral and helical. T/F

The largest of the viruses are similar in size to some small bacteria and are large enough to be seen with a light microscope. T/F

The presence or absence of an envelope is not useful in classifying viruses because any given virus may at one time have an envelope and at another time not have an envelope. T/F

Viruses such as MS2 and Qß pack additional information into their genomes through the use of overlapping genes. T/F

The simplest viruses consist of

Viral capsid protein subunits are called

In an enveloped virus, the part of the virus including the nucleic acid genome and the surrounding protein coat but not the envelope is called the

Some complex viruses have icosahedral symmetry in the head region and helical symmetry in the tail. Overall, these viruses are said to have __________ symmetry.

Glycoprotein spikes protruding from the outer surface of viral envelopes function as

A __________ genome exists as several separate, nonidentical molecules that may be packaged together or separately.

Many of the enzymes found in virus particles are

Which of the following is/are not true about viral envelopes?

Viral envelopes are composed of

Two major types of symmetry found in viruses include

The function of the viral protein coat is to

The protein coat surrounding the viral genome is called the

Which of the following is most true of a viral DNA genome?

Virion size ranges from

Viral capsids are generally constructed without any outside aid once the subunits have been synthesized. This process is called

In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their envelopes?

Most enveloped viruses use the host __________ membrane as their envelope source.

Poliovirus receptors are found

Nonenveloped viruses most often gain access to eukaryotic host cells by

Which of the following represent(s) the way(s) in which enveloped viruses acquire their envelopes?

Virus receptors are often not distributed uniformly over the surface of host cells, but are instead concentrated in lipid rafts. T/F

Enveloped viruses may enter their host cells by fusion of their envelope with the cytoplasmic membrane, thereby depositing their nucleocapsid within the cell. T/F

Enveloped viruses may enter their host cells by engulfment within coated vesicles (endocytosis). T/F

Some viruses cause abnormal growth of cells rather than destruction. This is called __________.

Human cancer causing viruses most often have a ___________ genome.

Adult T-cell leukemia is thought to be caused by

Genes whose expression (or abnormal expression) causes cancer are called

Which of the following has been associated with a form of liver cancer?

Microscopic or macroscopic degenerative changes or abnormalities in infected host cells and tissues are called __________ __________.

In a plaque assay, the number of infectious virions is usually identical to the number of virus particles present. T/F

Animal viruses have been cultivated in

Which of the following can be used to cultivate plant viruses?

0.2 mls of a 10-4 dilution of a virus preparation yields 90 plaques. What is the number of PFU per ml in the undiluted virus preparation?

A ________ assay is most useful for determining the viability of a viral preparation?

Hemagglutination is

Like bacteria and eukaryotic microorganisms, most viruses can be cultured using artificial media. T/F

Bacterial viruses are so named because they have prokaryotic cell structures similar to their bacterial hosts. T/F

Localized areas of destruction occurring on plants that have been infected by a virus are referred to as __________ lesions.

Which of the following is not a mechanism by which viruses cause cancer?

Which of the following is not true regarding the human hepatitis D virusoid?

Which of the following is not true of viroids

Viroids are of economic significance because they cause disease in

Viroids are:

Prions are of significance because they cause infections of

Which of the following diseases is (are) caused by prions?

Prions consist of proteins and have no apparent nucleic acid genome. T/F

Available evidence is consistent with the proposal that prion diseases are caused by infectious proteins. T/F

The mechanism of pathogenesis by prions may involve a conformational change in the prion protein (PrP) to an abnormal form. T/F

There are no known human diseases that have been linked to prions. T/F