Microbiology: Chapter 13 - Reading Assignment

Which are the two major categories of viral infections?

- Acute - Persistent

Which of the following statements about viruses are true?

- Viruses contain RNA or DNA but not both. - The viral capsid is composed of protein.

The major categories of animal viral infections are _____ infections, characterized by the sudden onset of symptoms of a relatively short duration, and _____ infections that can continue with or without symptoms for years.

- acute - persistent

Symptoms of acute viral diseases result from ______.

- host tissue damage - host immune response

Animal viruses can be studied by infecting ______.

- live animals - cell or tissue culture - fertilized chicken eggs

Signs of viral infections in plants include ______.

- yellowing of leaves - presence of tumors - stunted growth

Bacteriophages that exit the host cell at the end of an infection by lysing it are called _______ phages.

virulent

Infection of bacteria by _____ phages always ends with the lysis of the host cell.

virulent

_______ are viruses that are capable of infecting and selectively killing cancer cells.

Oncolytic viruses

Which form of transduction results from excision errors during the transition from a lysogenic to lytic cycle?

Specialized

During the _____ or maturation step in viral multiplication, capsids and genetic material are packaged into virions.

assembly

Infectious agents that have a simpler structure than viruses include ______.

both viroids and prions

Animal viruses ______.

can only be grown in animal cells

Oncoviruses are viruses that can ______.

cause cancer in humans

Although live animals and fertilized chicken eggs have been used to cultivate animal viruses in the past, these have now been largely replaced by _____ culture.

cell

Tumors are abnormal growths that result from a malfunction in the regulation of ______.

cell growth

When an enveloped virus gains entry to an animal cell by fusion, the virus envelope fuses with the ______.

cytoplasmic membrane

If viruses are present in high enough concentrations in a sample, they can be quantified directly using a(n) _____ microscope.

electron

The process by which a virus is taken up by a host cell as a result of the host cell's cytoplasmic membrane surrounding the virion to form a vesicle is called ______.

endocytosis

In the case of animal viruses, the molecules that viral spikes attach to on the host cell in order to gain entry are typically ______.

glycoproteins

The study of bacteriophages has advanced much faster than investigations on animal viruses in part because ______.

it is easier to grow bacterial cells than animal cells

The smallest virus is approximately 10 ______ in diameter.

nanometers

Viruses that can cause cancer in humans are known as _____ viruses.

oncogenic

Viruses that specifically target and kill cancer cells are called _____ viruses.

oncolytic

In a(n) ______, viral titer can be determined by counting clear zones in a monolayer of cells.

plaque assay

Which types of viruses are released by budding?

Enveloped viruses

It is easier to cultivate animal viruses than bacteriophages.

False

There is no need to classify viruses because they are not living organisms.

False

Which of the following phage types cause productive infections that do not kill the host cell?

Filamentous

_____ phages cause productive infections that do not kill the host cell.

Filamentous

Which form of transduction results from packaging errors during phage assembly?

Generalized

Attachment of animal viruses to the host cell typically occurs by means of ______.

spikes

A ______ phage can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage.

temperate

Bacteriophages that can enter into a lytic cycle or a lysogenic cycle are called _____ phages.

temperate

Viral infections in plants can cause diseases ______.

that are economically devastating

In acute viral infections, although the infected host cells may die, the host may survive because ______.

the host's immune system may gradually eliminate the virus

What term is used to describe the transfer of genetic information from one bacterium to another bacterium by a bacteriophage?

transduction

An abnormal growth of tissue resulting from a malfunction in the normally highly regulated process of cell growth is a _____.

tumor

A _______ is a single virus particle.

virion

A complete viral particle, which typically consists of nucleic acid surrounded by a protein coat, is called a(n)

virion

A(n) _____ is an infectious agent that lacks a capsid and consists only of RNA.

viroid

A generalized infection cycle of an animal viruses can be divided into five steps: 1. _____ ; 2. _____ entry ; 3. _____ ; 4. assembly ; and 5. _____.

1- attachment 2- genome 3- synthesis 5- release

In which type of infection does the virus remain in the host for years, sometimes without symptoms?

Persistent

Which of the following are non-cellular infectious agents composed of only a single-stranded RNA molecule?

Viroids

A prion is best described as ______.

a proteinaceous infectious agent

List the steps of an animal virus infection cycle in the correct order. Start with the earliest at the top.

1. attachment 2. penetration and uncoating 3. synthesis of viral proteins and replication of the genome 5. release

Which of the following describes the various viral parts coming together to produce virions?

Assembly

Why are bacteriophages easier to study than animal viruses?

It is easier to grow the bacteriophage host cells in the lab.

Which of the following about classifying viruses is FALSE?

It is not as important as classifying organisms since they are not living entities.

Match each possible outcome of phage replication with the correct definition.

Productive infection --- New viral particles are produced Latent state --- Viral genome remains silent within the cell

Human cells are larger than viruses by which size factor?

Thousand

All of the following are required for synthesis of new virus particles in a host cell EXCEPT ______.

homologous recombination

Viruses are best described as _______.

infectious agents

Which of the following describe a type of relationship that bacteriophages can have with their host?

- Latent infection where host cell genotype is changed - Productive lytic infection

Which of the following processes are required for production of virus particles in a host cell?

- Replication of viral genome - Transcription of viral genes - Translation of viral genes

Which of the following are non-cellular infectious agents?

- Viruses - Viroids - Prions

_____ transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle.

Specialized

An infectious agent that consists of protein and no nucleic acid is called a(n) _____.

prion

The stage of viral multiplication at which budding occurs is ______.

release

Bacteriophages play a fundamental role in a type of horizontal gene transfer called _____.

transduction

_____ transduction is the result of packaging errors during the assembly stage of phage replication.

Generalized

_____ infections remain for years, or even the lifetime of the host, sometimes without any symptoms.

Persistent