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BIO 120.01 > Viruses > Flashcards

Viruses Flashcards

1
Q

Identification

What is the first discovered virus? Who discovered it?

A

Tobacco Mosaic Virus (TMV)
Dmitri Ivanovsky

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2
Q

Define

What is a virus?

A
  • obligatory intracellular parasites

Extra
* macromolecular aggregates
* composed of inanimate particles that by themselves, cannot reproduce, metabolize, or carry functions associated with life.

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3
Q

Explain

Are viruses alive?

A

It depends!
* Outside hosts: virion, inert/inactive
* Once they enter the body, they begin to display the characteristics of life (reproduction, evolution)

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4
Q

Identification

Virus particle when found outside hosts

A

Virion

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5
Q

List

Viral characteristics

4

A
  1. Has a nucleic acid that functions as their genome (DNA or RNA)
  2. Has a capsid: Protein coat/shell that encloses genome
  3. Capsid can be enclosed within an outer envelope made up of lipids, proteins, and carbohydrates and taken from the host cells
  4. Have surface proteins along its surface
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6
Q

Identification

subunits that compose capsid

A

Capsomeres

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7
Q

Identification

capsid + viral genome (DNA/RNA)

A

nucleocapsid

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8
Q

Identification

  • allows virus to interact with receptor proteins in their host cell → leads to infection
  • determine the virus targets since they interact with specific receptors on the surface of their host cells
A

surface proteins

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9
Q

Identification

What is the spike in SARS-Cov-2 (causes COVID-19)?

A

Spike glycoproteins

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10
Q

Identification

In SARS-Cov-2 (causes COVID-19), what enzyme does its spike bind to?

A

angiotensin converting enzyme 2 (ACE2)

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11
Q

Identification

What are the 4 key characteristics for viral classification?

according to the video

A
  1. Genetic material
  2. Target host
  3. Capsid shape
  4. Enzymes they produce
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12
Q

Explain

What is the difference between an enveloped vs a naked virus?

A

Enveloped virus: nucleocapsid + outer envelope + spikes + surface proteins that help virus adhere to host

Naked virus: nucleocapsid + surface proteins

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13
Q

Identification

What is the virus with the most base pairs? How many base pairs does it have?

A

Pandoravirus, 2.74M base pairs

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14
Q

List

What are the different characteristics of the genetic material in a virus?

3

A
  1. Single-stranded/Double-stranded
  2. Linear/Circular/Segmented (Arrangement)
  3. Plus Sense/Minus Sense
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15
Q

T/F [Bonus: If false, what is wrong?]

In viruses, DNA can be single-stranded.

A

True
Although DNA is usually attributed as double-stranded, it can be single-stranded too.

Note: RNA can ONLY be single-stranded

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16
Q

List

How can viruses be arranged? What are these arrangements similar to?

3

A
  • Linear: like humans
  • Circular: like bacteria
  • Segmented: Unique to Influenza
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17
Q

Explain

Why is influenza hard to kill?

A

Can escape antibodies after vaccination bc nucleic acids mutate a lot

18
Q

List

What processes does influenza undergo that makes them stronger?

3

A

Antigenic drift
* accumulation of mutations
* Change arrangement of RNA → new strain

Antigenic shift
* 2 influenza viruses are on 1 individual
* RNA of 2 viruses mix

Alters surface proteins → become undetectable by present antibodies

19
Q

Explain

How does a plus sense virus turn into viral proteins?

A

same base sequence as viral mRNA → translation → viral proteins

20
Q

Explain

How does a minus sense virus turn into viral proteins?

A

Viral replication: complementary to viral mRNA → conversion → plus sense RNA counterpart → translation → viral proteins

21
Q

Identification

What is a plus sense virus that goes through a different process?

A

Family Retroviridae

22
Q

Explanation

How does the Family Retroviridae convert the virus to viral proteins?

A

plus sense single stranded RNA → reverse transcription → DNA → transcription → mRNA → translation → viral proteins

23
Q

Identification

What virus has the smallest size?

A

Polio virus (28 nm, around the size of a ribosome)

24
Q

Identification

What virus has the largest size?

Hint: It is so big that it can be viewed under a light microscope

A

Pithovirus

25
Q

List

What are the kinds of capsid shape? What symmetry do they have?

3

A
  1. Helical: rod-shaped symmetry
  2. Icosahedral: spherical symmetry
  3. Complex: Head + tail bacteriophages
26
Q

Identification

  1. capsid shape with rod-shaped symmetry
  2. Length: genome length
  3. Width: Capsomere arrangement length
  4. Ex.: Tobacco Mosaic virus, Ebola virus, Rabies virus
A

helical

27
Q

Identification

  • capsid shape with spherical symmetry
  • 20 triangular faces, 12 corners
  • Ex. poliovirus, herpes, influenza; many plant, animal, bacterial viruses
A

icosahedral

28
Q

Identification

  • capsid shape with Head + tail bacteriophages
  • Icosahedral head
  • Helical tail
  • Ex. T4 bacteriophage
A

Complex viruses

29
Q

List

What kinds of assembly do viruses go through?

2

A
  1. Self-assembly: assembly info is in their genomes
  2. Assisted assembly: need assistance of host cell’s chaperone proteins
30
Q

List

What are the subviral particles that cause disease?

2

A

viriods, prions

31
Q

Identification

  • Naked, single-stranded, cirular RNA with hairpin shaped structures
  • enters through a wound bc it can’t interact w/ host cell receptors
  • attributed to severall plant diseases
A

Viroids

32
Q

Identification

Give an example of a viroid disease.
What kind of symptoms do viroid diseases produce?

____ related symptoms

A

Cadang-cadang disease, growth related symptoms

33
Q

Explain

How do viroids infect the host?

A
  1. enters through a wound
  2. relies on host cell machinery to replicate
  3. moves across cells through plasmodesmata

Extra: they usually mimic or interfere with host regulatory RNAs that function for growth

34
Q

Identification

How viroids move from one cell to another

A

plasmodesmata

35
Q

Identification

  • cause transmissible spongiform encephalopathies which are uncurable neurodegenerative diseases
  • no DNA or RNA
  • can destroy the brain & other nervous tissue
A

Prions

36
Q

Identification

What does prions stand for?

A

proteinaceous infectious particles

37
Q

Explain

What is the mechanism of prions?

A
  1. Prion host cells (ex. Human cells) have Prion Protein (Prnp - gene)
  2. When Prnp is expressed → prion protein cellular (PrPC - protein)
  3. Prion Protein Scrapie (PrPSc - Pathogenic Prion) enters body → more PrPC becomes PrPSc by misfolding
  4. Amyloid formation
  5. Leads to transmissible spongiform encephalopathies (Alzheimer’s, Huntington’s, Parkinson’s, Type II Diabetes)
38
Q

Identification

  • uncurable neurodegenerative diseases
  • what prions are responsible for
A

transmissible spongiform encephalopathies

39
Q

Identification

  • insoluble crystalline fibers
  • what prions form
  • causes transmissible spongiform encephalopathies
A

amyloids

40
Q

Fill in the blank

Viroids are ____ that cause ____ diseases in ____, while
Prions are ____ that cause ____ diseases in ____.

A

RNA, growth-related, plants
proteins, neurodegenerative (nervous tissue related), animals

BIO 120.01 (12 decks)

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