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Introduction To Microbiology > Virus Structure And Life Cycle > Flashcards

Virus Structure And Life Cycle Flashcards

1
Q

Fill in this table.

A
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2
Q

What four things can viruses infect?

A
  1. Animals. 2. Plants. 3. Microbes. 4. Viruses.
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3
Q

Viruses are host selective. True or false?

A

True.

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4
Q

Define viral characteristics.

A

Genetic information contained within a protein coat, requiring a living cell in order to replicate.

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5
Q

What three things does viral characteristics contain?

A
  1. Genetic information in the form of RNA or DNA. 2. A protein capsid composed of capsomeres (for stability). 3. A receptor binding protein to enable cell entry.
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6
Q

What is the length of bacteria?

A

1000nm to 10,000nm.

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7
Q

What is the size of viruses?

A

30nm to 100nm.

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8
Q

What is the size of a poxvirus?

A

200nm to 400nm.

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9
Q

What is the size of a filovirus?

A

80nm in diameter and 9000nm to 14,000nm long.

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10
Q

What is the non-enveloped virus also referred to as?

A

The naked virus.

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11
Q

In reference to a non-enveloped virus, what does its capsid offer to the virus itself?

A

Protection and interaction with host receptors for cell entry.

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12
Q

Name three examples of a non-enveloped virus.

A
  1. Norovirus. 2. Papillomavirus (warts). 3. Poliovirus.
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13
Q

Label this diagram.

A
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14
Q

Define viral envelope.

A

A lipid bilayer taken from their host.

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15
Q

In reference to an enveloped virus, what three combinations of host cell does it consist of?

A
  1. Plasma membrane. 2.Nuclear membrane. 3. Trans Golgi network.
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16
Q

What are the spikes on an enveloped virus known as?

A

Carbohydrate-protein complexes.

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17
Q

Name three examples of enveloped viruses.

A
  1. Herpes virus. 2. Influenza. 3. Retroviruses.
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18
Q

State four features of an icosahedral viral shape.

A
  1. Spherical. 2. Limited amount of viral nucleic acid. 3. Has twenty equilateral triangular planes. 4. More capsomers means it’s more stable.
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19
Q

Define two features of a helical viral shape.

A
  1. Rod shaped so is flexible. 2. It contains large quantities of viral nucleic acid.
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20
Q

How does size size affect the complexity of the genome? Name two examples.

A

The larger the virus, the more complex the genome; such as poxviruses and bacteriophages.

21
Q

State four general properties of the extracellular state in regards to viruses.

A
  1. Minute particle (nm) - virion. 2. Nucleic acid and protein. 3. Metabolically inert. 4. Infectious potential which is measured in the periphery.
22
Q

State four general properties of the intracellular state in regards to viruses.

A
  1. Virus replication occurs. 2. Produces new copies of the viral genome using host machinery and viral factories. 3. Virus coat is snythesised. 4. Viral assembly occurs.
23
Q

Type A influenza can infect what?

A

Humans and animals.

24
Q

Type B influenza can infect what?

A

Humans.

25
Q

Type C influenza can cause what?

A

A mild respiratory infection, which is common. There is no vaccine.

26
Q

Label this diagram.

A
27
Q

What family does the influenza virion belong to?

A

Orthomyxoviridae.

28
Q

What is the diameter of the influenza virion?

A

80nm to 120nm.

29
Q

What are the five stages of viral lifecycle?

A
  1. Attachment. 2. Uncoating. 3. Viral replication, transcription and translation. 4. Viral assembly and packaging. 5. Budding or exocytosis.
30
Q

Define attachment in regards to the viral lifecycle.

A

Viral receptors attach to the host cell, leading to viral uptake.

31
Q

Define uncoating in regards to the viral lifecycle.

A

Release of genetic information.

32
Q

Define viral replication, transcription and translation in regards to the viral lifecycle.

A

It hijacks the cell machinery and down regulates host replication.

33
Q

Define epidemic.

A

Outbreak in a certain population at a certain time, such as seasonal winter outbreaks.

34
Q

Define pandemic.

A

Outbreak in an entire country or the whole world.

35
Q

What does HA stand for and what is its percentage?

A

Haemagglutinin (80%).

36
Q

What does NA stand for and what is its percentage?

A

Neuraminidase (20%).

37
Q

What is the function of HA?

A

It is a transmembrane protein involved in binding to host receptors and fusion for viral entry.

38
Q

What is the function of NA?

A

It is a integral membrane protein involved in viral assembly and release of new virus particles.

39
Q

All H and N types spread efficiently in humans, apart from what three?

A

H5, H7 and H9.

40
Q

How many subtypes of HA are there?

A

16.

41
Q

How many subtypes of NA are there?

A

9.

42
Q

Define antigenic drift in reference to viral reassortment.

A

The sequence changes in H and N proteins, it naturally occurs during seasonal outbreaks and it affects Influenza A and B.

43
Q

Define antigenic shift in reference to viral reassortment.

A

It is responsible for pandemics, there is no previous immune response and it only affects Influenza A.

44
Q

What three inactivated viruses does the flu vaccine contain?

A

2x A and 1x B/.

45
Q

What are viruses essential for?

A

Maintaining ecosystems.

46
Q

Who removed bacteriophages from sea water? What was their hypothesis?

A

Gunnar Bratbak (1990) expected to see an increase in bacterial life.

47
Q

What are the five stages of a bacteriophage lifecycle?

A
  1. Attachment. 2. Biosynthesis - replication of viral genome. 3. Expression of viral phage genes. 4. Assembly. 5. Release.
48
Q

How long does the lifecycle of a T4 bacteriophage take? How many new phages does this create?

A

It takes 30 minutes and produces around 150 new phages.

49
Q

What are four limitations of bacteriophage therapeutics?

A
  1. Combination can cause mild fever to death of the patient. 2. Have a narrow host range. 3. Humans immune system destroys the bacteriophage. 4. Some bacteria are resistant to infection.

Introduction To Microbiology (14 decks)

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