Microbiology Chapter 13: Viruses, Viroids, and Prions

mRNA

(+) strand genome serves as ________.

compliment to mRNA

(-) strand genome is the __________.

homologous recombination

All of the following are required for synthesis of new virus particles in a host cell EXCEPT ______. genome replication RNA synthesis homologous recombination protein synthesis

reverse transcriptase

An enzyme that uses an RNA molecule as a template to make a complementary copy of DNA is called _______.

obligate intracellular parasites

Because they are dependent on host cells, viruses are classified as ________.

certain host organelles the host cytoplasmic

Enveloped viruses can derive their envelopes from ______. certain host organelles the host cytoplasmic membrane the host matrix protein the environment

shift

Reassortment of gene segments that encode viral surface proteins that are recognized by the immune system can result in a loss of the immune system's ability to recognize and respond to the virus. This phenomenon is called antigenic ______.

electron microscope

Viruses can only be seen using what kind of microscope?

Integrase

What directs the incorporation of phage DNA into a bacterial chromosome?

Budding and triggering apoptosis

What mechanisms do newly assembled viruses use to leave their host cell?

Spikes/tail fibers

Which of the following are viral components that attach to specific receptors on host cells? spikes tail fibers capsomeres matrix

Persistent

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

Temperate; lytic

_______ phages have the option of entering the prophage state, while _______ phages always burst the host cell shortly after infection.

Specialized

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

Generalized

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

lysogenic

Some pathogenic bacteria produce toxins that are encoded on prophage DNA, and these are examples of _______ conversion.

host immune response host tissue damage

Symptoms of acute viral diseases result from _______. host immune response lysogenic conversion host tissue damage viral budding

titer

The concentration of infections phage particles in a sample is called the ______.

RNA polymerase or replicase

The enzyme of RNA viruses that lacks proofreading ability and thus makes many mistakes compared to the polymerases of DNA viruses is _______.

provirus

A _______ is an animal virus genome residing silently in a host cell genome.

latent

A viral infection in which the viral genome is integrated into an animal host cell chromosome, yet can reactivate to cause a productive infection, is categorized as a(n) ________ infection.

specialized, generalized

In ___________ transduction, only bacterial genes adjacent to the prophage can be transferred; whereas in _________ transduction, any bacterial gene can be transferred.

matrix protein

In enveloped viruses, sandwiched between the nucleocapsid and the envelope is the ________.

4,3,5,2,1

List the steps of an animal virus infection cycle in the correct order. 1.Release 2.Assembly 3.Penetration and uncoating 4.Attachment 5.Synthesis of viral proteins and replication of the genome

peptidoglycan

Lysozyme degrades _________.

nucleus

Most animal DNA viruses will replicate within the host cell's ________.

proteins and nucleic acids

at a minimum, all viruses are composed of __________.

Lysogenic conversion

________ is a change in the phenotype of a lysogen as a consequence of the specific prophage it carries.

actute; persistent

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.

burst

The number of phage particles released from a host cell is called the _____ size.

uncoating

The process by which the viral nucleic acid is released from the protective protein coat is _________.

glycoproteins

The protein receptor molecules on a host cell to which viruses attach by their spikes are typically __________.

retroviruses

Viruses that have an RNA genome and use reverse transcriptase to synthesize a DNA copy of that genome are called ________.

Translation of viral genes, replication of viral genome, and transcription of viral genes

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

specialized transduction

What type of transduction produces defective phage particles, transfers phage DNA and adjacent host genes, and results from errors in excision of the prophage?

Viroids

Which of the following are non-cellular infections agents composed of only a single-stranded RNA molecule? Viroids Plasmids Prions Virions Transposons

Prions, Viroids, and Viruses

Which of the following are non-cellular infections agents? Prions Fungi Bacteria Viroids Protozoa Viruses

viral spikes

Before enveloped viruses bud from a host cell, specific viral proteins insert into the host membrane. These proteins become _______.

No. Some types of viruses infect prokaryotic cells and others infect eukaryotic cells, but none infect both types of cells.

Can a virus infect prokaryotic cells and eukaryotic cells?

Chronic

The hepatitis B virus sometimes causes an infection that results in a continuous and low-level production of virus particles. This type of infection pattern is specifically described as a(n) _________ viral infection.

repressor

Which of the following proteins is essential for maintenance of the lysogenic state? integrase isomerase activator repressor lysozyme