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Microbiology > Acellular Agents, Ch13 > Flashcards

Acellular Agents, Ch13 Flashcards

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Biology 101 flashcards
1
Q

A miniscule acellular infectious agent having one or several pieces of nucleic acid, either DNA or RNA. The nucleic acid is the genome. Also lacks cytosol and functional organelles.

A

Viruses
(L. poison) - Name proposed by Pasteur for infectious particles smaller than bacteria, also called virions or viral particles.

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2
Q

Two states to viruses. One is inactive and crystalized. The other is active and infectious (alive or dead? not an organism)

A

Extracellular, virion

Intracellular

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3
Q

Genetic parasites that exploits host cell’s genetic and metabolic machinery in order to propagate themselves.

A

Obligate intracellular parasites (like viruses)

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4
Q

Host range is usually very specific. Viral glycoproteins attach to specific receptor sites on host cell membranes (some are known to parasitize all types of cells)

A

-tropism

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5
Q

Infect by attaching to the cell wall or flagella or fimbriae of bacteria. Complex structure with an icosahedral cubical head, a helical tail, and fibers for attachment.

A

Bacteriophages

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6
Q

Penetrate the host cell membranes by latching its spikes with cell receptors.

A

Animal viruses

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7
Q

Transmitted cell wall abrasions or by aphids and nematodes.

A

Plant viruses and viroids

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8
Q

Less known, transmitted when fungal cells fuse, no extracellular state.

A

Fungal viruses

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9
Q

The size range of viruses is what?

A

Normally ultramicroscopic, between 10nm-300nm on an electron microscope (the size of the smallest bacteria, mycoplasmas.

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10
Q

The protein coat of a virus that surrounds the genome (which is made of what?), used for protection and host cell attachment. What are both the coat and the genome together called?

A

Capsid
Either DNA or RNA, not both.
Nucleocapsid

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11
Q

Many medically important viruses also have what in addition to capsids?

A

An phospholipid membrane envelope and sometimes enzymes

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12
Q

Protein subunits that interlock to form these of distinctive shapes and configurations.

A

Capsomeres

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13
Q

A type of virus in which the capsids are composed of capsomeres that bond together to form a tube around the nucleic acid.

A

Helical, rod-shaped capsomeres that form a hollow disk

Eg influenza, measles, mumps, and rabies virus.

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14
Q

A type of virus in which the capsids are roughly spherical, with a shape like a dome. The most common type is this, with 20 triangular faces and 12 corners.

A

Polyhedral

Icosahedral

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15
Q

Viruses that have capsids of many different shapes that do not readily fit into either of the other two categories.

A

Complex
The complex shapes of many bacteriophages include isohedral heads, which contain the genome, attached to helical tails with tail fibers.

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16
Q

The classification of viruses is based on what according to the International Committee on the Taxonomy of Viruses (ICTV) formed in 1966?

A

Type of nucleic acids
Presence or not of envelope
Shape and size

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17
Q

The different types of genetic material that viruses can have?

A

Double-stranded DNA, dsDNA
Single-stranded DNA, ssDNA
Double-stranded RNA, dsRNA
Single-stranded RNA, ssRNA

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18
Q

The genome of any particular virus may be what, as in eukaryotic or prokaryotic cells?

A

Liner and composed of several molecules of nucleic acid, like eukaryotes
Singular and circular as in most prokaryotic cells.

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19
Q

A portion of the membrane system of a host cell, composed of a phospholipid bilayer and proteins. Some proteins are bound to the capsid, others are glycoproteins.

A

Envelope

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20
Q

Virally coded proteins, which appear as spikes protruding from the surface of the envelope. They function in attachment and invasion of host cells.

A

Glycoprotein spikes

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21
Q

Enveloped viruses help fusion with the host cell membrane for entry, but are susceptible to what?

A

Organic solvents, like alcohol

Detergents

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22
Q

So far, taxonomists have established what for viruses?

A

Have established families for all viral genera, but only three viral orders. Family is -viridae.
No kingdoms, divisions, or classes.

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23
Q

What are family and genus names for viruses?

Species and subspecies?

A

Family is -viridae.
Suffix “virus” used for genus name that is italicized.
Species names not latinized, but instead use common english designations, followed by a number for a subspecies.

24
Q

What are the five basic stages of viral replication?

A 
Attachment
Entry
Synthesis
Assembly
Release
25
Q

What do enveloped viruses use for the release of infectious viral particles during replication? Nonenveloped viruses?

A

Budding

Lysis

26
Q

Replication cycle in which the phage nucleic acid takes control (usually dsDNA) and the cell undergoes lysis near the end?

A

Lytic replication

Virulent phages

27
Q

Modified replication cycle of some bacteriophages in which the infected host cell’s chromosomes replicate together with the prophage for many generations before they lyse?

A

Lysogenic replication cycle
Lysogeny

Used by temperate or lysogenic phages, special DNA viruses

28
Q

Inactive bacteriophage that codes a protein that surpasses its genes. Inserted into the DNA of the bacterium, becoming a physical part of the bacterial chromosome in lysogeny.

A

Prophage

29
Q

The process whereby a prophage us excised from the host chromosome. Agents of this are usually the same physical and chemical agents that damage DNA molecules.

A

Induction
Lytic phase
Agents are UV, x-rays, carcinogens.

30
Q

When lysogenic phages change the DNA of a bacterium, for example from a harmless form into a pathogen.

A

Lysogenic conversion

31
Q

A process by which an animal viral capsid attaches and sinks into the cytoplasmic membrane, creating a pore through which the genome alone enters the cell.

A

Direct penetration

32
Q

A penetration method of animal viruses in which the entire capsid and its contents (including genome) enter the host cell by fusing with the plasma membrane and releasing into the cytoplasm.

A

Membrane fusion

33
Q

A penetration method of animal viruses in which the entire capsid and its contents (including genome) by attaching to the receptor molecules on the cell’s surface, stimulating it to do this.

A

Endocytosis, engulfment

34
Q

DNA viruses typically enter what, whereas RNA viruses enter what?

A

DNA-nucleus

RNA-replicated in cytoplasm

35
Q

A human virus with a genome composed of ssDNA

A

Parvovirus

36
Q

Single-stranded viral RNA that can act directly as mRNA, which ribosome can directly translate polypeptide proteins from the codons of.

A

Positive-strand RNA, +RNA
Sense strand RNA, +ssRNA

RNA-dependent RNA polymerase (eg poliovirus)

37
Q

A complementary strand transcribed from the +ssRNA genome by viral RNA polymerase. Serves as a template for the transcription of multiple +ssRNA genomes.

A

Negative-strand RNA, -RNA
Antisense genome, -ssRNA

Packaged with viral Rna polymerase (eg rabies)

38
Q

+ssRNA viruses that do not use their genome as mRNA, but instead use a DNA intermediary transcribed from +RNA by reverse transcriptionase carried within the capsid.

A

Retroviruses

ssRNA genome into dsDNA which enters the nucleus and becomes lysogenic forming a provirus or transcribed into new ssRNA.

39
Q

Virus where the positive strand serves as mRNA for the translation of proteins, one of which is an RNA polymerase that transcribes it. Each strand of RNA acts as a template for its opposite.

A

dsRNA viruses
Parent strand remains intact and the progeny RNA molecule is completely new, conservative replication. Copy of a copy, eg retroviruses.

40
Q

When animal viruses remain dormant in cells. It may prolonged for years with no viral activity, signs, or symptoms. The viral incorporation is permanent.

A

Latency

Latent viruses, proviruses

41
Q

Diagnosis by signs and symptoms. Some are typical while others show multiple manifestations. Others mimic other infections.

A

Clinical

42
Q

Diagnosis by examination (LM)- affected tissues for inclusion bodies (e.g. Negri bodies in rabies)

A

Microscopic

43
Q

Diagnosis by examination (TEM) –electron microscopy (shadow casting –> gold dust and negative staining using heavy metals like OsO4)

A

Ultramicroscopic

44
Q

Diagnosis by testing for antibodies. Titers taken at onset and peak of infection (4-fold rise in titer = active infection).

A

Serologic

45
Q

Diagnosis techniques – quick screening but problems with false positive and false negatives. Use monoclonal antibodies to improve these techniques (e.g. ELISA and latex agglutination tests)

A

Antigen detection techniques

46
Q

Diagnosis by looking for cytopathogenic effects (CPE) for animal viruses on monolayers, or plaques in the case of bacteriophages.

A

Cell culture techniques

47
Q

For propagation of viruses for vaccine production. Inexpensive, among the largest of cells, free of contamination, and self-scuffient nourishment.

A

Embyronated eggs

48
Q

Nucleic acid analysis that detects and amplifies even minute amounts of DNA or RN. Very sensitive but background problems.

A

Polymerase chain reaction

49
Q

Nucleic acid analysis that uses DNA segments to detect common sequences of viruses.

A

Gene probes

50
Q

Areas on a cell culture of a virus where the phages have lysed the bacteria.

A

Plaques

Plaque assays are where eat plaque corresponds to a single phage in the original bacterium-virus mixture.

51
Q

Extremely small, circular pieces of ssRNA without capsids that are infectious and pathogenic in plants.

A

Viroids
Cadang disease in coconuts
Viroidlike agents infect some fungi but not plants.

52
Q

This virus is latent in nerve cells, with an eruption later triggered by changes.

A

Herpes simplex virus-fever blisters and genital herpes.

Herpes zoster virus-chickenpox and shingles.

53
Q

Proteinaceous agent that lacked instructional nucleic acid. Clumps of their beta-pleated PrPsc encourage cellular PrPc to refolding into PrPsc.

A

Prions
Nine animal diseases. Mad cow disease in people, causing spongiform encephalopathy. May be linked to some genetic diseases.

54
Q

Slow viral infection that usually lasts months or years. It’s usually fatal. Examples?

A

Persistent viral infection
HIV-dementia results from brain degeneration.
Measles-encephalitis causing mental deterioration

55
Q

Gross changes in the cell

Compacted masses of viruses or damaged cell organelles.

A

Cytopathogenic effects

Inclusion bodies

56
Q

Cell transformation causing cancer. 10% of all cancers.

A

Oncogenic viral effects

HPV and liver cancer

Microbiology (8 decks)

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