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Biology > Viruses > Flashcards

Viruses Flashcards

1
Q

Do viruses reproduce?

A

No, they use host cells to make copies of themselves

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2
Q

What are the proteins on the surface of viruses useful for?

A

They’re important for attaching to and entering cells

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3
Q

What are the 2 ways that viruses evolve?

A
  • Antigenic Drift
  • Antigenic Shift
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4
Q

How does antigenic drift work for viruses?

A
  • When small changes in the virus occur gradually through the accumulation of mutations
  • Viruses undergo slow or limited evolution
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5
Q

How does antigenic shift work for viruses?

A
  • Viruses show rapid evolution when they infect a new host species
  • Large abrupt changes that occur, often because cell has been infected by multiple viruses (from more than one species)
  • When a shift happens, most people have little to no protection/immunity against the new virus
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6
Q

What contributes to our susceptibility to contracting Influenza year after year?

A

Antigenic drift

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7
Q

Because of what will seasonal flu change over the course of the year? What also causes the need for flu vaccines every year or 2?

A

Antigenic drift

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8
Q

What’s an epidemic?

A

An unexpected increase in the number of disease cases in a specific geographical area

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9
Q

What’s a pandemic?

A

An epidemic that spreads across countries and/or continents

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10
Q

What’s an endemic?

A
  • When a disease is consistently present in a particular region. This makes the disease spread and disease rates predictable.
  • We know how to deal with endemic (masks, social distancing)
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11
Q

What are the 2 forms of direct transmission?

A
  • Person-to-person contact
  • Droplet transmission
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12
Q

What’s person-to-person transmission?

A

Transmission that results from coming into contact with another person (or their bodily fluids)
Ex: HIV or Ebola

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13
Q

What’s droplet transmission?

A

When a host sneezes or coughs on another
Ex: Covid and Influenza
Larger droplets = respiratory droplets
Smaller droplets = droplet nuclei

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14
Q

What are the 3 forms of indirect transmission?

A
  • Airborne transmission
  • Vector Transmission
  • Waterborne Transmission
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15
Q

What’s airborne transmission?

A

Droplet nuclei from evaporated droplets or dust particles containing bacteria or virus are suspended in the air and enter the respiratory system
Ex: tuberculosis, chickenpox

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16
Q

What’s vector transmission?

A

Getting picked up by a carrier (ex: a mosquito) and carried into a new host
Ex: malaria

17
Q

What’s waterborne transmission?

A

Leaving one host and infecting the water supply and being taken up by a new host
Ex: cholera

18
Q

What’s virulence?

A

How much the virus/bacteria affects the host’s fitness

19
Q

What’s a way to think of virulence?

A

Think of it as the reproductive output of the virus/bacteria

20
Q

More virulence means…

A

Less chance for transmission

21
Q

Less virulence means…

A

More chance for transmission

22
Q

What will the fitness of the virus/bacteria depend on?

A

How virulent and transmissible it is

23
Q

Natural selection should favour viruses/bacteria that achieve a balance between what?

A

How severe the disease they cause is (virulence) and how easy it is for hosts to catch it (transmissibility)

24
Q

The H1N1 Influenza virus is an example of an antigenic drift or shift?

A

Antigenic shift

25
Q

What was the difference in virulence between H1N1 and 1918 flu?

A

H1N1 = highly transmissible but not very virulent
1918 flu = highly virulent and transmissible

26
Q

Why was it mainly young adults dying of the 1918 flu?

A
  • The virus triggered an immune response and since young adults are among those with the strongest immune system, they were affected with the highest virulence
  • Also because young adults were among those that were mostly in the trenches at the time
27
Q

Which virus is the direct ancestor of all seasonal and pandemic flus over the last century?

A

The 1918 flu

28
Q

What 3 viruses did pandemics arise from?

A
  • Influenza
  • Ebola
  • Coronavirus
29
Q

Is ebola virulent?

A

Yes, it’s incredibly virulent with high death rates
- It’s swift and lethal

30
Q

Is transmissibility for ebola high?

A

Not as high since you can only catch it from direct contact (with bodily fluids)

31
Q

Where does the virulence in ebola come from?

A

From the over activation of the immune system (it sort of attacks itself) (cytokines)

32
Q

How is COVID transmitted?

A

Through respiratory droplets and contact

33
Q

What 2 factors are important for droplet transmission viruses (Especially COVID)

A
  • Location
  • Time
34
Q

All 3 viruses (ebola, influenza and COVID) share what about the immune system?

A

They all affect the immune system in a way where it’ll sometimes go haywire

35
Q

What do PCR tests do with DNA and RNA?

A

They amplify them
These are very sensitive to the virus

Biology (4 decks)

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