Chapter 13 LearnSmart

Infections that have a sudden onset of symptoms of relatively short duration are described as ________.

Acute

The study of viruses is important because ___________.

Bacteriophages play a significant ecological role in reducing bacterial populations in nature, there are many medically important viruses that cause disease, viruses can be a vehicle for horizontal gene transfer in bacteria

A viral capsid is made up of subunits called _____________.

Capsomeres

Which of the following are classified as persistant infections?

Chronic infections and latent infections

True or False: Lysogens are more susceptible to reinfection by the same type of phage

False

True or False: Most bacteria engulf bacteriophages as part of the phage replication strategy

False

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

Filamentous

Late proteins of the T4 lytic cycle include __________.

T4 capsomere components and T4 tail fibers

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

Temperate; lytic

Which facts best support the position that viruses are not living organisms?

Viruses are inert outside of a host and viruses cannot reproduce on their own.

What is a true statement about viruses?

Viruses contain RNA or DNA but not both and the viral capsid is composed of protein

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

burst

Viral genomes can be _________.

either single-stranded or double-stranded

Viral genomes can be ____________.

either single-stranded or double-stranded

M13 particles are assembled during a process called _________, which the virus uses to exit the cell.

extrusion

True or False: There is no need to classify viruses because they are not living organisms.

false

The term ____________ is used to describe the rupture or bursting of a cell.

lysis

One of the early proteins expressed in the T4 lytic cycle is an enzyme called a _______ that degrades the bacterial DNA.

nuclease

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

persistent

What are the three general shapes of most viruses?

Complex, helical, icosahedral

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

integrase

Lysogens are protected against infection by the same phage because the phage-encoded repressor protein binds to the ___________ on the incoming phage, preventing expression of the phage genes.

operator

At a minimum, all viruses are composed of __________.

proteins and nucleic acids

Which facts best support the position that viruses are not living organisms?

Viruses cannot reproduce on their own and viruses are inert outside of a host

Rank the following by size, from smallest to largest: human cells, viruses, bacteria.

Viruses, bacteria, human cells

The term ________ is used to describe the rupture or bursting of a cell.

lysis

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

provirus

Virus infections that result in the information of new virus particles are described as _____________.

productive

A virus acuired by inhalation would be called a(n) _____________.

respiratory virus

Symptoms of acute viral diseases result from __________.

Host immune response and host tissue damage

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

cell growth

In the lytic cycle of the T4 page, lysozyme degrades a portion of the bacterial ____________.

cell wall

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.

chronic

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

chronic

The M13 phage has a single-stranded DNA genome. Its replicative form is a double-stranded DNA molecule. The second strand of DNA is synthesized by ________.

host DNA polymerase

Consequences of lysogeny include _________.

immunity to superinfection and lysogenic conversation

Consequences of lysogeny include _____________.

immunity to superinfection and lysogenic conversion

Describe viruses

infectious agents

How does bacteriophage nucleic acid enter the host cell?

injection

Viral proteins that stick out from the viral envelope or capsid and attach to host cell receptors are termed __________.

spikes

Phage DNA and proteins are made during the _________ stage of the T4 lytic cycle.

synthesis

The study of viruses is important because ______.

there are many medically important viruses that cause disease, bacteriophages play a significant ecological role in reducing bacterial populations in nature, and viruses can be a vehicle for horizontal gene transfer in bacteria

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

Match each possible outcome of phage replication with the correct definition: productive infection and latent state.

Productive infection: new viral particles are produced Latent state: viral genome remains silent within the cell

True or False: Bacteriophages are important medically because they can be used to prevent the growth of food-contaminating pathogens

true

Which are two main criteria used in classifying viruses?

Genome structure and host range

Match each tumor to the correct statement: malignant and benign.

Malignant: spreads to nearby tissue Benign: does not spread to nearby tissue

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

Persistent

Viruses that infect bacteria are called __________.

Phages; bacteriophages

Match each gene type with the correct description: proto-oncogene and tumor suppressor gene.

Proto-oncogene: stimulates cell growth Tumor suppressor gene: inhibits cell growth

Which of the following are viral protein components that attach to specific receptors on host cells?

Tail fibers and spikes

Viruses are challenging to study because ________.

They can only be seen using an electron microscope and they are obligate intracellular parasites

To maintain the lysogenic state, a ________ protein prevents expression of the gene required for excision.

repressor

The binding of a bacteriophage surface protein to a host cell receptor is called ________.

attachment

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

lysogenic

Which of the following describes a consequence of lysogeny that could result in human disease?

lysogenic conversation

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

matrix protein

Which of the following occur during the synthesis stage of the T4 lytic cycle?

synthesis of phage DNA, degradation of bacterial DNA, synthesis of phage proteins