Micro Ch. 13
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.
