CH 26- VIRUS

Check all of the correct statements regarding the use of metagenomics to describe viral diversity.

-Metagenomics has identified thousands of new viral species. -Samples with the viruses are first analyzed by PCR.

statements about bacteriophage

-do not have envelope -A temperate phage can have its DNA integrated into the host chromosome as a prophage. -A prophage is replicated with the bacterial chromosome and passed to the two new daughter cells. - ultraviolet light can cause induction

plant virus

RNA and capsid

The gene for a receptor protein in a bacterial cell membrane has become mutated. This protein is the same receptor that is recognized by the T4 phage. What effect will this have on the bacterial cell?

The bacterial cell will be immune to T4 phage infection, but will be impaired by missing its normal receptor.

A bacterial cell was discovered to have viral DNA incorporated into its genome. Which statement best explains this observation?

The cell or one of its ancestors was infected by a lysogenic phage.

A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the

envelope

Tetracycline is effective against viruses because it disrupts the action of the viral ribosomes

false

The pneumonia caused by the influenza virus results from the accumulation of fluid and cell debris in the lungs. This occurs during the lysogenic life cycle of the virus

false

The drug AZT

inhibits the enzyme reverse transcriptase

a class of infectious proteins with no associated nucleic acid have been identified. They are referred to as

prions

mad cow is caused by

prions

While they are simple relative to cells, viruses often have a very diverse collection of components. Which one of the following choices is LEAST likely to be found as part of a virus?

ribosome

During a prion infection, the disease causing PrP serves as a template for replication.

true

The viral envelope contains some components that are from the host cell's genome and some from the viral genome

true

the correct statements below that we have learned from using metagenomics as a tool to better understand viral ecology.

1. In one liter of coastal water there are 10 times more viruses than bacteria 2.Since only a small fraction of viruses cause disease in animals and plants, it is hard to isolate virsues. 3. Soil and water are good sources to analyze for virus metagenomics.

Viruses grown in media with radioactive sulfur have radioactive capsids. Why?

Cysteine amino acids contain sulfur

adenovirus

DNA and capsid

bacterial virus

DNA, capsid, tail

How is an enveloped virus structurally different from a phage, like T4

Enveloped virus possess an additional membrane around their protein capsid, phage do not possess a membrane.

An experimental chemical has been shown to selectively cleave phosphodiester bonds. How would this affect a virus?

Fragment the genome

Which of the following statements about the types and subtypes of the influenza (flu) virus is FALSE?

Genetic recombination between influenza and other types of viruses is common

Gardasil is marketed as a cervical cancer vaccine, but it is actually a human papilloma virus (HPV) vaccine. Why is this done?

HPV in the cervical epithelial cells may cause the cells to become cancerous

Integrase inhibitors work by:

Preventing the incorporation of the viral DNA into the genome

influenza

RNA, capsid, envelope, and antigen

Viruses may cause cancer in these three typical ways:

Some viruses encode an oncogene in their genome. A viral genome may integrate into the host chromosome, disrupting a cell cycle gene. Some viral proteins interact with cell cycle regulatory proteins.

Diseases such as scrapie in sheep, "mad cow" disease in cattle, and Creutzfeldt-Jakob disease in humans are known as

TSEs (transmissible spongiform encephalopathies).

A mutation in the gene encoding the integrase enzyme renders the protein non-functional. How would this affect-the HIV infection cycle?

The viral DNA would not be able to integrate the viral genome into a chromosome

All of the following are diseases caused by viruses

aids, polio, small pox, measles, rabies, says, influenza, ebola, mononucleosis, herpes, hepatitis, chicken pox

The protein gp120, involved in binding to the cell surface of host cells, is a glycoprotein. This means that it is linked to what nonproteinaceous molecule

an oligosaccharide

Outside the protein sheath, many viruses have a(n) _______ made of protein, lipid, and carbohydrate.

envelope

If the viral gene is AUGCCCAGG and the mRNA used to make the viral protein is UACGGGUCC, then the virus is a

negative strand RNA virus

Viruses are ______ -coated fragments of DNA or RNA.

protein

Most viruses form a capsid around their nucleic acid core. This capsid is composed of

proteins

What kind of pathogen would retain its ability to cause infections after being treated with powerful proteolytic chemicals that would destroy all proteinaceous material?

viroid