Micro Ch. 13

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A viroid is a circular molecule of ssRNA with a capsid. False True

false

Animal cells do not contain latent viruses. True False

false

One characteristic first used to name viruses was host range. capsid structure. DNA composition. disease type.

host range.

A (n) _____is a 20-sided polyhedral capsid. icosahedron lysogenic lytic temperate

icosahedron

Virus vaccines are always cultured in embryonated chicken eggs. False True

False

Viruses cause MOST human cancers. False True

False

Double-stranded DNA genomes are found only in viruses in both cells and viruses only in cells only in viroids

in both cells and viruses

Genes that play a role in proper cell division but may also play a role in some types of cancer are called _____. progenes protooncogenes good genes bad genes

protooncogenes

The most common polyhedral virus has_____triangular surfaces. 30 20 10 50

20

Put the following stages of a lytic replication cycle in order, from earliest to latest stages: I. Synthesis (Biosynthesis) II. Assembly (Maturation) III. Attachment IV. Release V. Entry (Penetration)

III, V, I, II, IV

Who was the first person to demonstrate the existence of viruses? Prusiner Stanley Ivanowsky Rous (Real scientist, but no relation!)

Ivanowsky

Prions are composed of a single protein called _____. (Be sure to use proper capitalization.) Prion PrP Protein Particle

PrP

Which of the following individuals discovered prions? Stanley Rous (Real scientist, but no relation!!) Iwanowsky Prusiner

Prusiner

Which scientist purified and crystallized the tobacco mosaic virus? Griffith Stanley Iwanowsky Beijerinck

Stanley

It enters the lytic or lysogenic pathway. Virulent Temperate

Temperate

The phage combines with the host cell without damage. Temperate Virulent

Temperate

How are prions different from all other known infectious agents? They act as slow viruses. They cannot reproduce outside a cell. They cause neurological problems. They lack nucleic acid.

They lack nucleic acid.

Select the INCORRECT statement about viruses. They show signs of life outside of host cells. They are parasites. All cellular organisms are attacked by them. They contain nucleic acids inside a protein coat.

They show signs of life outside of host cells.

AZT inhibits reverse transcription in the AIDS virus. False True

True

Many diseases of plants are caused by infectious RNA molecules lacking capsids. False True

True

Protozoa are susceptible to viral attack. True False

True

It enters only the lytic pathway. Virulent Temperate

Virulent

Its attack is swift and deadly. Temperate Virulent

Virulent

Which of the following statements concerning viruses is FALSE? Some viruses have an outer membrane called an envelope. Tobacco mosaic virus was the first virus to be discovered and characterized. Virus capsids can assume one of three basic shapes. Viruses enter a cell to complete the replication that they have begun extracellularly.

Viruses enter a cell to complete the replication that they have begun extracellularly.

During the intracellular state, a virus exists as a lipid a lipid and a protein a nucleic acid a protein

a nucleic acid

The tail fibers of an animal virus are destroyed. This will directly interfere with the _____stage of the life cycle of this virus. penetration. uncoating. absorption. adsorption.

adsorption.

Proteins are present in cells only viroids only both cells and viruses viruses only

both cells and viruses

Host specificity of a virus is due to interactions between viral and cellular surface molecules presence of an envelope genes that are shared with the infected cell presence of a cell wall on the host cell

interactions between viral and cellular surface molecules

Virus replication results in the death of the cell in a(n)_________infection. latent persistent oncogenic lytic

lytic

Tumors invade other organs and tissues in a process called metastasis neoplasia budding latency

metastasis

Virus infection results in cancer in the process of budding oncogenesis lytic replication latency

oncogenesis

Double-stranded RNA genomes can be found only in cells in both cells and viruses in prions only in viruses

only in viruses

Viroids infect plants fungi all organisms bacteria

plants

The outermost layer of a virion fulfills which of the following functions of the virus? protection replication protection and recognition recognition

protection and recognition

The virus capsid consists of nucleic acid. protein. lipid. carbohydrate.

protein.

Reverse transcriptase is associated with which of the following? dsRNA viruses retroviruses dsDNA viruses ssDNA viruses

retroviruses

Shingles is a disease mainly affecting the blood. skin. muscles. bones.

skin.

Another term for a lysogenic phage is a _____phage. lytic temperate viroid virulent

temperate

RNA viruses such as HIV require the activity of reverse _____to become proviruses. virusase proteinase prionase transcriptase

transcriptase

A suspension with viruses and bacteria is passed through a filter. Each pore has a diameter of 500 nanometers. The viruses will probably pass through the filter but the bacteria will be trapped. True False

true

A temperate phage can act like a virulent phage or exist in host cells without harming the cells. True False

true

Adsorption is responsible for the tissue specificity of animal viruses. True False

true

A bacteriophage is (a) bacterium that infects bacteria. virus that infects viruses. virus that infects bacteria. bacterium that infects viruses.

virus that infects bacteria.


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