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BIO 220 [Exam #1] > Ch. 13 - Viruses, Virioids, and Prions > Flashcards

Ch. 13 - Viruses, Virioids, and Prions Flashcards

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1
Q

What is the size range for viruses?
(what unit of measurement do we use to measure them)

A

wide range of sizes, but are VERY small

use nanometer (nm) (compared to bact. micrometer)

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2
Q

How is viral structure unique?

A
  • acellular = not cells; no cytoplasm/CM/organelles
  • single type of nucleic acid is present = DNA or RNA
    -> viruses start off as either DNA or RNA virus
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3
Q

What are the structural components of a typical virus?

Briefly draw these structures and label them

A

(Genetic) Core: contains genetic material; DNA/RNA; AKA Genome

Capsid: surrounds/protects core; composed of capsomere proteins

Envelope: surrounds capsid (optional)

Spikes: attach to envelope (optional)

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4
Q

Viruses DO NOT ____________.

A

reproduce

Instead, they MULTIPLY

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5
Q

Where do viruses multiply?

A

inside living host cells (REQUIRED)

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6
Q

Describe what is meant when viruses are referred to as “obligate intracellular parasites”

A

this means viruses must enter inside of a living host cell and will cause harm to the host

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7
Q

TRUE or FALSE: A plant virus will infect an animal cell

A

False, because viruses show host specificity

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8
Q

TRUE or FALSE: Viral Hepatitis will infect the brain.

A

False, because viruses also show tissue specificity.

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9
Q

Understand host specificity and tissue specificity of viruses

Include examples

A

Host specificity = virus will only attack a specific host (Bacterial virus; bacteriophage will attack bacterium)

Tissue specificity: virus will only infect specific tissue (Viral Hepatitis infects liver; Viral Encephalitis infects brain)

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10
Q

Name some ways in which viruses are transmitted

A

by food, water, air, insects, direct contact

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11
Q

What is meant by “phage”

A

virus

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12
Q

PRACTICE:

What is a bacteriophage?
What is the host cell for a bacteriophage?

What is phage DNA?
Whose DNA does it belong to?

A

bacterial virus
bacteria

viral DNA
virus

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13
Q

Name the different “shapes”/morphology of viruses

Briefly describe and know/draw the shape

A

helical viruses (cylindrical head)
polyhedral virses
complex viruses

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14
Q

TRUE or FALSE: A complex virus will be found in an animal host cell.

A

False, because complex viruses are bacterial viruses, meaning it will only attack bacteria (bc of host specificity)

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15
Q

Describe the taxonomy of viruses

Include any information/examples about them

A

Family - Highest Taxon
- ends in -viridae
- ex: Herpesviridae, Retroviridae, Coronaviridae

Genus
- ends in -virus
- enterovirus, influenzavirus

Viral Species - Lowest Taxon
- A group of viruses sharing similar genetic information and ecological niche (host)
-> HIV (humans) and SIV (apes)
- Viral subspecies/strains
-> HSV-1; HSV-2; Influenza H1:N1

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16
Q

Describe the growth of Bacteriophages in the labroratory

Include what it will grown on, what does it form?

A

Bacteriophages are bacterial viruses, so they will be grown on a bacterial lawn on a plate

Plaques will form, which are areas of dead/damaged bacterial cells and no bacterial growth is happening in these areas
-> corresponds to single virus
-> expressed as PFU

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17
Q

Describe how animal viruses are grown in lab

A

grown in living animals, embryonated eggs, or animal cultures
-> virally infected animal cell is detetected via its deterioration, called cytopathic effect (CPE)

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18
Q

What is CPE (cytopathic effect)?

A

visible damage done to animal host cell
is specific/unique to animal host cell

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19
Q

How are viruses identified?
Which is the most common method?

A

Cytopathic effects (CPE): for animal virus identification\

Serological tests: MOST COMMON METHOD; look for the virus or antibody against virus

Polymerase Chain Reaction (PCR): isolate some viral DNA to make many copies

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20
Q

What is required in order for a virus to multiple?

A

must invade living host cell

virus must take over hosts metabolic machinery (host DNA); will telll the host DNA to make viral parts and to assemble them

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21
Q

What two cycles can Bacteriophages multiply by?

Describe

A

Lytic Cycle: required; causes lysis and death of bacterial host cell

Lysogenic Cycle: optional; does NOT cause death -> host cell divides; phage DNA embedded into bacterial host cell’s DNA = hybrid DNA/prophage

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22
Q

What is a virion?

A

newly-formed, mature virus
this is what leaves the bacterial host cell

23
Q

Briefly describe the two options Bacteriophages have to multiply

A

Option #1: Enter and complete Lytic cycle ONLY -> Bacterial host cell death

Option #2: Enter Lytic cycle only and then pause -> enter and complete Lysogenic cycle (bacterial host cell divides and host already infected) -> Re-enter and complete Lytic Cycle -> host cell death

24
Q

What are the stages of the Lytic Cycle for Bacteriophages?

Briefly describe them

A
  1. Attachment = to bacterial host cell
  2. Penetration = of phage DNA into host cell
  3. Biosynthesis = making the viral parts
  4. Maturation = assembly of viral parts
  5. Release = of virions -> will leave host cell and destroy host
25
Q

Describe ATTACHMENT of the LYTIC CYCLE

A
  • bacterial virus uses its tail fibers to attach to the cell wall receptors of bacterial host cell
  • viral lysozyme (enzyme) makes hole in bacterial cell wall (so that viral DNA can enter host cell; bacterial virus does NOT enter)
26
Q

Describe PENETRATION of the LYTIC CYCLE

A
  • viral sheath is contracted which will push the viral DNA into bacterial host cell
  • viral DNA now present in bacterial host cell
27
Q

Describe BIOSYNTHESIS of the LYTIC CYCLE

A
  • viral DNA incorporates into bacterial host DNA and takes over bacterial host cell’s DNA
  • Bacterial host forced/committed to make viral components (proteins) through transcription and translation
    (hybrid DNA –transcription-> RNA –translation–> protein)
28
Q

Describe MATURATION of the LYTIC CYCLE

A
  • viral components get assembled into virions
  • virions are newly-made, mature viruses capable of infecting other cells
29
Q

Describe RELEASE of the LYTIC CYCLE

A
  • bacterial host cell lyses/ruptures when new virions are released
  • results in death of bacterial host cell
30
Q

Define Lysogeny

A

phage DNA integrates and remains dormant (delay in biosynthesis) in a host cell; phage particle (protein) production is delayed

31
Q

Define prophage

A

“hybrid” DNA; is when phage DNA gets incorporated into host cell (bacteria) DNA

32
Q

How does Lysogeny happen?

A

Phase DNA get incorporated into host cell DNA -> forms Prophage (hybrid DNA)

When host cell replicates, it also replicated the prophage and DOES NOT lead to the production of phage particles in host cell (delayed biosythesis)

33
Q

Name and understand the 3 consequences of lysogeny

Include examples when possible

A

Phage Conversion: non-pathogenic bacteria becomes pathogenic bacteria

Latent Viral Infections: virus “hides out” in tissue (usually NS); symptoms decrease (ex: Shingles, Herpes)

Transformation: viruses turn-on cancer-causing genes (ex: HPV -> cervival cancer)

34
Q

At what point does the Lysogenic Cycle start after the Lytic Cycle begins in terms of Bacteriophages?

A
  • Attachment
  • Penetration
  • 1/2 Biosynthesis (formation of prophage)

- LYSOGENIC CYCLE STARTS AND FINISHES

  • 2/2 Biosynthesis (make protein particles)
  • Maturation
  • Release
35
Q

TRUE or FALSE: The multiplication process for animal viruses can be/is involved with the Lytic Cycle and Lysongenic Cycle

A

True

36
Q

What are the stages of multiplication (Lytic Cycle) for animal viruses?

A

- Attachment
- Entry: by RME (non-envelope) or fusion (envelope)
- Uncoating: viral/host enzyme get ride of capside to expose genetic core
- Biosynthesis
- Maturation
- Release: by budding (envelope) or rupture (non-envelope)

37
Q

Compare presence of envelope between animal viruses and bacteriophage

A

bacteriophage: non-enveloped
animal virus: non-eveloped or enveloped

38
Q

Name two ways in which a virus can enter an animal host cell

A

Fusion: for enveloped virus
Receptor Mediated Endocytosis (RME): for non-eveloped virus

39
Q

After entry of capside into animal host cell, _________ _________ must be ________ to ________ the ________ ________

A

protein capsid
disintegrated
expose
viral DNA

40
Q

When animal viruses DNA incorporates into the animal host cells DNA, it forms a ________________.

How is this different from bacteriophages?

A

provirus

When viral DNA is integrated into bacterial DNA, it forms a prophage

41
Q

At what point does the Lysogenic Cycle start after the Lytic Cycle begins in terms of Animal Viruses?

A
  • Attachment
  • Entry
  • Uncoating
  • 1/2 Biosynthesis (formation of provirus)

- LYSOGENIC CYCLE STARTS AND FINISHES

  • 2/2 Biosynthesis (making viral parts)
  • Maturation
  • Release
42
Q

Compare the type of nucleic acid found in Bacteriophages vs. Animal Viruses

A

Bacteriophages = DNA

Animal Viruses = DNA or RNA

43
Q

Animal viruses can exist either as DNA or RNA.

How does provirus formation differ between an animal virus containing DNA vs. an animal virus containing RNA?

A

DNA:
- animal virus DNA can incorporate into animal host cell’s DNA to form a provirus

RNA:
- animal virus RNA CANNOT incorporate into animal host cell’s DNA
- animal virus RNA must get converted into DNA by enzyme Reverse Transcriptase via Reverse Transcription -> can now incorporate into animal host cells DNA to form provirus

44
Q

Name 2 ways in which animal virus is released from the animal host cell

A

Budding: enveloped animal virus (buds out of animal host cell using its CM)

Rupture: non-enveloped animal virus

45
Q

Compare and Contrast:
Bacterial Viruses from Animal Viruses

Include similar or differences in: anatomy, cycle/stages, “hybrid” DNA names, DNA/RNA virus, enveloped/non-enveloped, how viral DNA enters host cell, and any other extra info/

A

Bacterial Virus:
- sheath
- tail fibers
- penetration stage
- prophage
- DNA virus only
- Non-enveloped viruses
- only genome (DNA) enters host cell; virus does not enter

Animal Virus:
- entry and uncoating stage
- provirus
- DNA or RNA viruses
- enveloped and non-enveloped
- entire virus enters host cell
- capable of reverse transcription

BOTH:
- capsid
- lytic and lysogenic cyel
- Attachment, Biosytnehsis, Maturation, Release stages
- “multiplication”
- obligate intracellular parasites

46
Q

Name some families that are DNA viruses and RNA viruses.
Include examples

A

DNA viruses:

  • Poxviridae
    -> smallpox, cowpox
  • Herpesviridae
    -> cold sores, genital herpes, chickenpox, shingles

RNA viruses

  • Retroviridae
    -> HIV/AIDS, COVID-19
47
Q

Some cancers are caused by viruses called ________

A

oncoviruses

48
Q

Describe oncoviruses
(how do they develop, and how do they cause cancer?)

A
  • may develop after viral infection
  • some oncovirses can turn on “oncogenes” found in normal cells -> uncontrolled cell division -> transform normal cells into cancerous cells
49
Q

Explain how oncoviruses turn on oncogenes

A

oncoviruses DNA becomes integrated into the host cell’s DNA and induces tumor (turns on oncogenes and cancer develops)

50
Q

Name the three “categories” of infections

Describe them and include examples.

A

Acute Viral Infections:

  • rapid onset of symptoms and short duration of infection
  • ex: influenza

Latent Viral Infections

  • hidden, inactive, dormant infection (virus hides)
  • ex: cold sores, genital herpes, shingles

Persistent/Chronic Viral Infections

  • late onset of symptoms, long duration, subclinical/mild symptoms
  • ex: HIV/AIDS
51
Q

Define/Describe Viriods

A
  • smallest infectious pathogens in the world
  • infectious RNA molecules
  • causes plant disease (ex: Potato disease)
52
Q

Define/Describe Prions

A
  • infectious protein particles (NO CURE)
  • highly resistant = destroy via incineration
  • cause transmissible neurological disease (ex: Spongiform Encephalitis)
53
Q

List several examples of Spongiform Encephalitis

A
  • Mad Cow Disease (Bovine Spongiform Encephalopathy); in cows
  • Creutzfeldt-Jakob Disease (CJD); in humans
  • Sheep Scrapie; in sheep

BIO 220 [Exam #1] (6 decks)

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