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BIO150 > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

What are some general characteristics of viruses?

A
  • Obligatory intracellular parasites (require living host cells to multiple)
  • Contain DNA or RNA
  • Contain a protein coat
  • No ribosomes
  • No ATP-generating mechanism
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2
Q

What is a host range?

A
  • The spectrum of host cells a virus can infect
  • Most viruses infect only specific types of cells in one host (determined by specific host attachment sites and cellular factors)
  • Bacteriophages
  • Range from 20 nm to 1000 nm in length
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3
Q

Bacteriophage

A

viruses that infect bacteria

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4
Q

Viral Structure

A

Viron - complete, fully developed viral particle

  • nucleic acid
  • Capsid
  • Envelope
  • Spikes
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5
Q

Describe the viral structures of DNA/RNA

A

DNA or RNA can be single or double stranded; linear or circular

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6
Q

Capsid

A

Part of the viral structure;

Protein coat made of capsomeres (subunits)

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7
Q

Describe the viral structure of the envelope

A

lipid, protein, and carbohydrate coating on some viruses

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8
Q

Describe spikes and their viral structure

A

projections from outer surface

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9
Q

General morphology of viruses includes what 4 types?

A
  • Helical virus - hollow, cylindrical capsid
  • Polyhedral viruses - many-sided
  • Enveloped viruses - lipid, protein coating
  • Complex viruses - complicated structures
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10
Q

Taxonomy of Viruses:

  • Genus names end in _____
  • Family names end in _____
  • Order names in end _____
A
  • -virus
  • -viridae
  • -ales
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11
Q

Viral Species

A
  • a group of viruses sharing the same genetic information and ecological niche (host)
  • Descriptive common names are used for species
  • Subspecies are designated by a number
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12
Q

Viruses must be grown in ______ cells.

A

living

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13
Q

Bacteriophages are grown in bacteria.

Bacteriophages form ________, which are what?

Each ________ corresponds to a single ______ and can be expressed as _______.

A

plaques

plaque, virus; plaque-forming units (PFU)

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14
Q

What are three main ways of growing animal virusesin the laboratory?

A
  • In living animals
  • In embryonated eggs
  • In cell cultures
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15
Q

What happens when you grow an animal virus in an embryonated egg?

A
  • The vrus is injected into the egg
  • The viral growth is signaled by changes or death of the embryo
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16
Q

What happens when animal viruses are grown in cell cultures?

A
  • Tissues are treated with enzymes to separate cells
  • Virally infected cells are detected via their deterioration, known as the cytopathic effect (CPE)
  • Continuous cell lines are used
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17
Q

T/F

Viruses are acellular

A

True

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18
Q

Viruses do/do not use binomial nomenclature

A

Do not

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19
Q

Virion

A

Complete, fully developed viral particle.

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20
Q

T/F

Nucleic acid - DNA or RNA in viruses can be single or double stranded

A

True

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21
Q

Capsid

A

Protein coat made of capsomeres

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22
Q

Capsomeres

A

Subunits of the capsid protein coat

23
Q

Envelope

A

lipid, protein, and carbohydrate coating on some viruses

24
Q

Spikes

A

projections from the outer surface of the envelope of a virion

25
Q

Can you draw the structure of a virion? How would you describe it? How would you describe its DNA/RNA?

A

Remember these main structures: capsid (capsomeres), envelope, spikes, the DNA or RNA can be either single or double stranded

26
Q

Helical viruses

A

Viruses that have a hollow, cylindical capsid

27
Q

How would you describe/draw the structure of a polyhedral virus?

A

Many sided

28
Q

How would you describe the structure of an enveloped virus?

A

A protein, lipid, and carbohydrate structure surrounding a capsid which holds a virus

29
Q

How would you describe complex structures of viruses?

A

Generally complicated. A good example is a bacteriophage (pictured).

30
Q

Viral species

A

a group of viruses sharing the same genetic information and ecological niche (host)

Descriptive common names are used for species

Subspecies are designated by a number

31
Q

What kind of cells must viruses be grown in?

A

living

32
Q

What types of cells are bacteriophages grown in?

A

bacteria

33
Q

plaques

A

Bacteriophages form placques, which are clearings on a lawn of bacteria on the surface of agar

Each plaque corresponds to a single virus; can be expressed as plaque-forming units (PFU)

34
Q

What are three different ways that animal viruses can be grown in labs?

A

Living animals

Embryonated eggs

In cell cultures

35
Q

What is the indicatio of viral growth in embryonated eggs?

A

Viral growth is signaled by changes or death of the embryo.

36
Q

Cytopathic effect (CPE)

A

Virally infected cells are detected via their deterioration

37
Q

Continuous Cell Lines

A

Cells that have acquired the capacity for infinite growth and division

Usually derived from tumor cells or transplanted cells (cells that become resistant to factors associated with growth control, produce cancer in animals)

38
Q

How are viruses identified?

A
  • Cytopathic effects
  • Serological testing
    • Western blotting - reaction of the virus with antibodies
  • Nucleic acids
    • RFLPs
    • PCR
39
Q

RFLP

A

Restriction Fragment Length Polymorphism

DNA profiling technique

40
Q

What two things must a virus have to multiply?

A
  • It must invade a host cell
  • It must take over the host’s metabolic machinery
41
Q

Sketch a one-step growth curve graph

Explain the decrease and increase of growth in the graph

A

Initial decrease: Virus has entered cell, but no progeny virions are created yet.

Steady increase: virions are being created

Decrease: cell death results in virions being released

42
Q

Lytic cycle

A

Bacteriophage multiplication in which phage causes lysis and death of the host cell

43
Q

Lysogenic Cycle

A
  • Phage DNA is incorporated in the host DNA
  • Phage conversion
  • Specialized transduction
44
Q

Specialized transduction

A
  • Bacterial genes can be picked up in a phage coat and transferred to another bacterium in a process called generalized transduction
  • Changes genetic properties of the bacteria
45
Q

What are the five steps of the Lytic cycle?

A
  • Attachment: phage attaches by the tail fibers to the host cell
  • Penetration: phage lysozyme opens the cell wall; tail sheath contracts to force the tail core and DNA into the cell
  • Biosynthesis: production of phage DNA and proteins
  • Maturation: assembly of phage particles
  • Release: phage lysozyme breaks the cell wall
46
Q

Lysogeny

A

Phage remains latent

47
Q

Lysogenic cycle

A
  • Phage DNA incorporates into host cell DNA
    • Inserted phage DNA is known as prophage
    • When the host cell replicates its chromosome, it also replicates prophage DNA
    • Results in phage conversion - the host cell exhibits new properties
48
Q

Phage conversion

A

Host cell exhibits new properties

49
Q

Steps of multiplication of animal viruses

A
  • Attachment: viruses attach to the cell membrane
  • Entry by receptor-mediated endocytosis or fusion
  • Uncoating by viral or host enzymes
  • Biosynthesis: production of nucleic acid and proteins
  • Maturation: nucleic acid and capsid proteins assemble
  • Release by budding (enveloped viruses) or rupture
50
Q

Where is DNA of a virus replicated in a host cell?

Where are capsids synthesized?

A

DNA is replicated in the host’s nucleus

Capsids are synthesized in the cytoplasm using the host cell enzymes

51
Q

Characteristics of picornaviridae

A

Single stranded RNA, + strand, nonenveloped

52
Q

Name a few RNA viruses and what family they belong to

A
  • Family: Picornaviridae
    • Single stranded RNA, + strand, nonenveloped
      • Enterovirus
        • Poliovirus and coxsackievirus
      • Rhinovirus
        • Common cold
      • Hepatitis A virus
53
Q

T/F

Viral cancers are contagious

A

False

54
Q
A

BIO150 (15 decks)

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