question

Acellular infectious agents

answer

Viruses

question

Scientist that studies viruses

answer

Virologist

question

Study of viruses

answer

Virology

question

Complete virus particle. Consists of >or = 1 DNA and RNA may have additional layers Cannot reproduce independent of living cells nor carry out cell division. But can exist extracellularly

answer

Virion

question

Simple organization

answer

Viruses

question

Carry out cell division

answer

Cellular organisms

question

Some obligate intracellular parasites

answer

Cellular organisms

question

Unable to reproduce outside living cells

answer

Viruses

question

Both DNA and RNA

answer

Cellular organisms

question

Obligate intracellular parasities

answer

Viruses

question

Complex organization

answer

Cellular organisms

question

DNA or RNA but not both (one exception)

answer

Viruses

question

True or False. Virions infect all cell types

answer

True

question

Bacterial viruses

answer

Bacteriophages

question

Virions are classified into families based on:

answer

Genome structure; Life cycle; Morphology; Genetic relatedness

question

localized area of cellular destruction and lysis

answer

plaques

question

microscopic or macroscopic degenerative changes or abnormalities in host cells and tissues

answer

Cytopathic effects

question

Suitable animals Embryonated eggs Tissue (Cell) cultures

answer

Hosts for animal viruses

question

Usually cultivated in broth or agar cultures of suitable, young, actively growing bacteria. Broth cultures lose turbidity as viruses Plaques observed on agar cultures

answer

Hosts for Bacteriophages

question

Plant tissue cultures Plant protoplast cultures Suitable whole plants

answer

Hosts for Viruses

question

Used to determine quantity of viruses in a samples

answer

Virus assays

question

Two types of approaches for Virus assays

answer

Count particles Measure concentration of infectious units

question

Types of count particles

answer

Direct counts and Indirect counts

question

Made with an electron microscope

answer

Direct counts

question

Determines highest dilution of virus that causes red blood cells to clumb together

answer

Hemaggluntinaton assay

question

Dilutions of virus preparation maded and plated on lawn of host cells. Number of plaques counted

answer

Plaque assays

question

Plaque assays are expressed in what units?

answer

Plaque forming units

question

Size range of virions

answer

10-400 nm in diameter

question

How are most virions viewed

answer

Through an electron microscope

question

True or False. All virions contain a nucleocapside

answer

True

question

Nucleic acid held with protein coat

answer

Nucleocapsid

question

Protein coat that surrounds a viral genome Protects genome and aids in transfers between host cells.

answer

Capsid

question

Protein sub-units that make up capside

answer

Protomer

question

Shaped like hollow tubes with protein walls

answer

Helical capsids

question

Regular polyhedron with 20 equilateral triagular faces and 12 vertices

answer

Icosahedral Capsid

question

Ring or knob shaped units made of five or six protomers

answer

Capsomers

question

Five subunit capsomers

answer

Pentamers (pentons)

question

Six subunit capsomers

answer

Hexamers (hexons)

question

membrane structures surrounding some viruses

answer

Viral envelope

question

proteins in envelop -virus specific

answer

Peplomers (spikes)

question

Observed in some viruses Associated with or are within capsid

answer

Viral enzymes

question

True or False. Viruses fit into the category of having helical or Icosahedral capsids

answer

False

question

Largest animal virus

answer

Poxvirus

question

Binal symmetry

answer

Large bacteriophages

question

Having both icosahedral and helical symmetry

answer

Binal symmetry

question

Sequence of nucleotides in genomic RNA= sequence of nucleotides in viral mRNA

answer

Plus strand RNA viruses

question

Sequences of nucleotides in genomic RNA is complementary to viral mRNA.

answer

Minus strand RNA viruses

question

Virions contains >1 unique RNA.

answer

Segmented genomes

question

Sequences of viral infection

answer

1. Attachment to host cell (Adsorption) 2. Entry 3. Uncoating of genome 4. Synthesis 5. Assembly 6. Release

question

specific receptor attachment that determine host preference (specific tissue, more than one host, more than one receptor, lipid rafts providing entry of virus)

answer

Attachment (Adsorption)

question

Phage life cycle that culminates with host cell bursting, releasing virions

answer

Lytic cycle

question

Phages that lyse their host during the reproductive cycle

answer

Virulent phages

question

Specific surface structures on host to which viruses attach. Specific for each virus Can be protein, lipopolysaccharides, techioc acids, etc.

answer

Receptor sites

question

Contains hydroxymethylcytosine instead of cytosine and is synthesized by two phages encode enzymes then HMC glucosylated

answer

Synthesis of T4 DNA

question

Protects phage DNA from host restriction

answer

HMC glucosylation

question

Enzymes that cleavage DNA at specific sequences

answer

Endonucleases

question

Use of restriction endonucleases as a define mechanism against viral infection

answer

Restriction

question

Aid in construction of procapsid

answer

Scaffolding proteins

question

Attacks peptidoglycan

answer

Endolysin

question

produces lesion in cell membrane

answer

Holin

question

nonlytic relationship between a phage and its host

answer

Lysogeny

question

integrated phage genome

answer

Prophage

question

Infected bacterial host

answer

lysogens

question

phages able to establish lysogeny

answer

temperate phages

question

Rapid onset and relatively short duration

answer

acute infections

question

can last many years

answer

persistent infections

question

Virus almost always detectable. Clinical symptoms mild or absent for long periods

answer

Chronic virus infection

question

Virus stops reproducing and remains dormant for some time.

answer

Latent infections

question

Deletion of mutant that cannot reproduce and slowsreproduction of normal virus

answer

Detective interfering particle

question

Growth or lump of tissue

answer

tumor

question

abnormal new cell growth or reproduction due to loss of regulation

answer

neoplasia

question

reversion to a more primitive or less differentiated state

answer

anaplasia

question

spread of cancerous cells through body

answer

metastasis

question

Complex multistep process. Involves oncogenes Cancer causing genes Many involved in regulation of cell growth and differentiation

answer

Carcinogenesis

question

Infectious agents composed only of circular ssRNA

answer

Viroids

question

infectious agent thought to be composed only of protein

answer

Prions

question

Do not act as mRNA molecules Cause disease to plants Mechanism unknown Some cause latent infections RNA may be replicated by rolling circle method using host RNA polymerase

answer

Viroids

question

Cause degenerative diseases in animales

answer

Prions

question

When a viral genome is integrated into the host chromosome but does not result in the lysis of the host cell, it is referred to as A. temperate infection. B. avirulent infection C. lysogemy D. alytic infection

answer

C. lysogemy

question

Which of the following is not true of viroids? A. Viroids are small circular ssRNA molecules. B. Viroids have no protein capsids. C. Viroids do infect plants and some procaryotic cells D. All of these are true of viroids.

answer

D. All of these are true of viroids.

question

Which of the following is not true of viroids? A. Viroids are small circular ssRNA molecules. B. Viroids have no protein capsids. C. Viroid RNA does not serve as mRNA nor does it direct the synthesis of mRNA. D. Extracellular viroids have a lipid bilayer envelope.

answer

D. Extracellular viroids have a lipid bilayer envelope.

question

Which of the following can serve as phage receptor sites? A. lipopolysaccharides and teichoic acids B. pili C. membrane proteins D. All of these can serve as phage receptor sites

answer

D. All of these can serve as phage receptor sites

question

True or False The presence or absence of an envelope is not useful in classifying viruses because any given virus may at one time have an envelope and at another time not have an envelope.

answer

False

question

Viral capsid protein subunits are called A. auxomers B. elastomers C. protomers D. viromers

answer

C. protomers

question

Which of the following is true about viral envelopes? A. The envelope proteins are virus specific B. The envelope lipids and carbohydrates are derived from the host C. Both of these answers are true D. Neither of these answers are true

answer

C. Both of these answers are true

question

Which of the following is most useful in determining the viability of a viral preparation? A. a direct (electron microscopic) count B. hemagglutination C. a plaque assay D. All are equally useful in determining the viability of a viral preparation

answer

C. a plaque assay

question

The function of the viral protein coat is to A. protect the viral genetic material B. aid in the transfer of the viral genetic material between host cells C. both protect the viral genetic material and aid in the transfer of the viral genetic material between host cells D. neither protect the viral genetic material nor aid in the transfer of the viral genetic material between host cells

answer

C. both protect the viral genetic material and aid in the transfer of the viral genetic material between host cells

question

Attachment of a bacteriophage to its host is mediated by A. specific surface proteins on the bacteriophage B. specific receptor proteins on the host cell C. both specific surface proteins on the bacteriophage and specific receptor proteins on the host cell D. either specific surface proteins on the bacteriophage or specific receptor proteins on the host cell but not both

answer

C. both specific surface proteins on the bacteriophage and specific receptor proteins on the host cell

question

True or False The injection mechanism used by bacteriophages whereby the nucleic acid penetrates the cell leaving the protein coat outside is not used by any known animal viruses.

answer

False

question

A __________ genome exists as several separate, nonidentical molecules that may be packaged together or separately. A. diploid B. segmented C. polyploid D. fractionated

answer

B. segmented

question

Viruses with single-stranded RNA as their genome for which the base sequence is the same as the viral mRNA are said to be __________ viruses. A. plus-stranded B. minus-stranded C. mRNA-like D. None of these

answer

A. plus-stranded

question

In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their envelopes? A. penetration B. component biosynthesis C. assembly D. release

answer

D. release

question

Which of the following is not true of viruses? A. Viruses are acellular. B. Viruses consist of one or more molecules of DNA or RNA enclosed in a coat of protein and sometimes in other more complex layers. C. Viruses are obligate intracellular parasites. D. Viruses replicate by binary fission.

answer

D. Viruses replicate by binary fission.

question

Which of the following is not true of viruses? A. Viruses are acellular B. Viruses consist of one or more molecules of DNA or RNA enclosed in a coat of protein and sometimes in other more complex layers. C. Viruses are obligate intracellular parasites. D. All of these are true of viruses.

answer

D. All of these are true of viruses.

question

45. The nucleic acids carried by viruses usually consist of A. DNA B. RNA C. either DNA or RNA but not both simultaneously D. both DNA and RNA simultaneously.

answer

C. either DNA or RNA but not both simultaneously

question

47. Most important character in viral classification is: A. nucleic acid type (DNA or RNA) B. nucleic acid strandedness (single or double) C. presence or absence of an envelope D. all of the choices

answer

A. nucleic acid type (DNA or RNA)

question

Viruses are subgrouped according to A. nucleic acid type (DNA or RNA) B. nucleic acid strandedness (single or double) C. presence or absence of an envelope D. all of the choices

answer

D. all of the choices

question

Viruses with single-stranded RNA as their genome for which the base sequence is the same as the viral mRNA are said to be __________ viruses. A. plus-stranded B. minus-stranded C. mRNA-like D. none of these

answer

A. plus-stranded

question

True or False The presence or absence of an envelope is not useful in classifying viruses because any given virus may at one time have an envelope and at another time not have an envelope.

answer

False

question

Which of the following is (are) a function(s) of late viral proteins? A. formation of the virion capsid B. assembly of mature virions by noncapsid proteins C. lysis of host cells D. all of the choices

answer

D. all of the choices

question

The protein coat surrounding the viral genome is called the A. capsule B. capsid C. matrix D. envelope

answer

B. capsid

question

The function of the viral protein coat is to A. protect the viral genetic material B. aid in the transfer of the viral genetic material between host cells C. both protect the genetic material and in the transfer of genetic material between host cells D. neither protect the viral genetic material nor aid in transfer of the viral genetic material between between host cells

answer

C. both protect the genetic material and in the transfer of genetic material between host cells

question

True or False Like bacteria and eucaryotic microorganisms, viruses can be cultured on artificial media.

answer

False

question

Which of the following is true about viral envelopes? A. The envelope proteins are virus specific. B. The envelope lipids and carbohydrates are derived from the host C. Both of these answers are true D. Neither of these answers is true

answer

C. Both of these answers are true

question

Animal viruses can be cultivated in A. suitable host animals B. embryonated eggs C. tissue cultures (monolayers of animal cells) D. all of these

answer

D. all of these

question

Animal viruses can be cultivated in A. suitable host animals B. embryonated eggs C. tissue cultures (monolayers of animal cells) D. all of these E. Only A and C

answer

D. all of these

question

True or False Bacterial viruses are so named because they have the same procaryotic cell structure as their bacterial hosts.

answer

False

question

The nucleic acids carried by viruses usually consist of A. DNA B. RNA C. either DNA or RNA but not both simultaneously D. both DNA and RNA simultaneously

answer

C. either DNA or RNA but not both simultaneously

question

In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their envelopes? A. penetration B. component biosynthesis C. assembly D. release

answer

D. release

question

A __________ assay is most useful for determining the viability of a viral preparation. A. direct (electron microscopic) count B. hemagglutination C. plaque D. PCR

answer

C. plaque

question

The two major types of symmetry found in viruses are A. icosahedral and radial B. icosahedral and helical C. helical and radial D. radial and bilateral

answer

B. icosahedral and helical

question

True or False The largest of the viruses are similar in size to some small bacteria and are large enough to be seen with a light microscope

answer

True

question

Which of the following morphologies are found among the bacteriophage? A. tailless phage with icosahedral symmetry B. tailed phage with binal symmetry C. filamentous phage with helical symmetry D. All of these are found in a bacteriophage

answer

D. All of these are found in a bacteriophage

question

Some viruses do not have A. capsid B. nuclei acid C. protomer D. envelope

answer

D. envelope

question

True or False Enveloped viruses may enter their host cells by fusion of their envelope with the cytoplasmic membrane, thereby depositing their nucleocapsid within the cell.

answer

True

question

True or False A few viruses are as large as smallest bacteria

answer

True

question

The largest viruses known are the A. herpesviruses B. hepadnaviruses C. adenoviruses D. poxviruses

answer

D. poxviruses

question

Hemagglutination is A. the clumping together of red blood cells in the presence of a viral suspension B. the binding of iron in the process of a viral suspension C. the clumping together of infected cells in the presence of a viral suspension D. None of these

answer

A. the clumping together of red blood cells in the presence of a viral suspension

question

In an enveloped virus, the part of the virus including the nucleic acid genome and the surrounding protein coat but not the envelope is called the A. capsid B. nucleocapsid C. matrix D. virion

answer

B. nucleocapsid

question

A complete virus particle is called a A. capsid B. nucleocapsid C. virion D. cell

answer

C. virion

question

What is a feature of a virus with a segmented genome? A. It has multiple chromosomes B. It is haploid C. It has a genome composed of separate pieces D. It must have a DNA genome

answer

C. It has a genome composed of separate pieces

question

Which of the following lists the steps of viral activity in the correct order, from start to finish? A. Attachment, lysis, penetration, replication B. Lysis, penetration, replication, attachment C. Attachment, penetration, replication, lysis D. Penetration, replication, attachment, lysis

answer

A. Attachment, lysis, penetration, replication

question

True or False Enveloped viruses may enter their host cells by engulfment within coated vesicles (endocytosis)

answer

True

question

175. A biochemist wants to control the initial substrate-level phosphorylation that occurs in the yeast cells once glucose has crossed the plasma membrane. This means that he will: A. have to prevent cAMP from entering the tracheal cells B. have to prevent pyruvate reduction from occurring C. have to prevent glycolysis from occuring in the mitochondria D. have to prevent aerobic respiration in the cytoplasm E. have to prevent glycolysis from occuring in the cytoplasm

answer

E. have to prevent glycolysis from occuring in the cytoplasm

Microbiology: Chapter 27 – Flashcards

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