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Cycle 3 - Infection > Viruses > Flashcards

Viruses Flashcards

1
Q

What are Viruses ?

A

Infectious agents that require a host in order to replicate

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2
Q

What do ‘obligate parasites’ lack ?

A

The mechanism for metabolic energy/protein synthesis

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3
Q

How are viruses classified ?

A

1) By morphology
2) Chemical composition
3) Mode of replication

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4
Q

What are virons (virus particles) assembled from ?

A

They’re assembled from pre-formed components

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5
Q

Name the pre-formed components virons are assembled from ?

A

1) Genome - which contains either DNA or RNA
2) Protein shell (Capsid) - together w/genome = Nucleocapsid
3) Membrane envelope
4) Outer layer (for protection and for recognition sites of host cells)

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6
Q

Give an example of a ‘non-serious’ virus and the infection it causes

A
  • Rhinovirus - causes a cold
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7
Q

Give an example of ‘serious’ viruses

A
  • Enteroviruses
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8
Q

Give examples of sever diseases caused by viruses

A

1) Rabies

2) Ebola

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9
Q

What is the importance of the Capsid of a virus ?

A

It allows for classification of a virus

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10
Q

Name 3 classes of Viruses ?

A

1) Helical
2) Icosahedral (formed by capsomers)
3) Complex

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11
Q

What is meant by a Naked virus ?

A

Virus that has a capsid only and no envelope

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12
Q

What is meant by an Enveloped virus and what is the envelope made out of ?

A

The capsid is surrounded by an envelope which is made out of Lipids and proteins

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13
Q

Name an example of complex virus

A

bacteriophage T4

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14
Q

Give 3 functions of the the Capsid

A

1) Protection -from the hosts acid and from protein-digesting enzymes
2) Assists in binding and penetrating host cell
3) Stimulates the host’s immune system

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15
Q

The nucleocapsid of an enveloped virus is more flexible than that of a naked virus. TRUE or FALSE ?

A

TRUE

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16
Q

Envelope spikes (glycoproteins) consist of carbohydates and protein complexes which are used in attachment to host cell. TRUE or FALSE ?

A

TRUE

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17
Q

Virus DNA or RNA can be double (ds) or single stranded (ss). TRUE or FALSE ?

A

TRUE

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18
Q

ssRNA further divides into Positive and Negative polarity. TRUE or FALSE ?

A

TRUE

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19
Q

DNA viruses fall into class 1, 2 AND 7. TRUE or FALSE ?

A

TRUE

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20
Q

RNA viruses fall into class 3-6. TRUE or FALSE ?

A

TRUE

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21
Q

RNA viruses show very rapid rates of mutation. TRUE or FALSE ? and why ?

A

TRUE, because they DO NOT have proof-reading abilties

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22
Q

DNA polymerases possess proof reading abilities, therefore less mutations and evolve less rapidly. TRUE or FALSE ?

A

TRUE

23
Q

Give 2 mechanisms Viruses may use to evade detection ?

A

1) Change their antigens, therefore they’re not recognised

2) Generalised immune response

24
Q

How many stages of the Viral cycle are there ? Name them.

A

6

1) Attachment
2) Penetration
3) Uncoating
4) Genome replication
5) Assembly of virion particle
6) Release

25
Q

Many viral infections are not silent. TRUE OR FALSE?

A

FALSE

26
Q

What does the outer layer of a virus do?

A

It provides protection and it is the recognition site for host cells

27
Q

How are viruses classified?

A

By morphology and chemical composition/mode of replication

28
Q

The capsomere does not forms the main building blocks of isohedral structure. TRUE OR FALSE?

A

FALSE

29
Q

Icosahedral virus can be enveloped (with a capsid) or naked (without a capsid). TRUE OR FALSE?

A

TRUE

30
Q

Give an example of a non enveloped icosahedral virus?

A

Adenovirus

31
Q

Helical viruses can be enveloped or naked. TRUE OR FALSE?

A

TRUE

32
Q

What does a helical virus assemble into together with viral nucleic acid?

A

Helical structure

33
Q

Give an example of a non enveloped and non enveloped helical virus?

A

non -Ebola

Influenza is enveloped

34
Q

What are complex viruses made up of?

A

Repeated units of a single polypeptide protomer

35
Q

What structures does Complex viruses together with nucleic acid form?

A

Helical structure

36
Q

What is enveloped spike involved in?

A

Recognition and attachment

37
Q

What are the mechanism that viruses used to avoid detection?

A
  1. Changing their antigens, so not recognised

2. Generalises immune suppression

38
Q

What does reverse transcriptase produce?

A

It uses a single stranded RNA genome to create a double stranded DNA

39
Q

Reverse transcriptase , involves DNA to RNA. TRUE OR FALSE?

A

TRUE

40
Q

What occurs during the initial contact of a viral infection?

A

Glycoproteins on the surface bind to cell surface

41
Q

What are the two different phases during initial contact of viral infection?

A

Reversible phase - electrostatic repulsion reduced

Irreversible phase - initiation of viral penetration

42
Q

What two mechanisms are initiated during the conformational changes of the anti-receptor - receptor complex?

A

Endocytosis (cell membrane is engulfs virus)

Fusion of viral envelopes and cell membrane (releases capsid into cytosol)

43
Q

What are the two main routes of virion release?

A

Lysis

Budding

44
Q

How are enveloped and non enveloped viruses released?

A

Enveloped - By budding

Non enveloped - By lysis

45
Q

What does Hepatitis cause?

A

Inflammation of the liver

46
Q

Hepatitis A - highly contagious, contamination is via water, it is a mild infection and can be self resolving. TRUE OR FALSE?

A

TRUE

47
Q

Hepatitis B and C does not spread through body fluid and can cause long term disease. TRUE or FALSE?

A

FALSE

48
Q

HBV is a small DNA virus that replicates through an RNA intermediate and can integrated into host genome. TRUE OR FALSE?

A

TRUE

49
Q

The synthesis of influenza mRNAs and replication occurs in the nucleus. TRUE OR FALSE?

A

TRUE

50
Q

For normal RNA viruses where does replication and synthesis occur?

A

In the cytoplasm

51
Q

What are the two subtypes that influenza A is divided into?

A

Hemagglutin (H)

Neuraminidase (N)

52
Q

What are the stages of HIV?

A

Acute infection - HIV replicates rapidly, CD4 count drops

Clinical latency - Virus replication much slower/immune system becomes compromised due to low CD4 count

AIDS - acquired immunodeficiency syndrome / immune system severely compromised / vulnerable to infections and infection related cancers.

53
Q

Some viruses induce (bring about) cancer. TRUE OR FALSE?

A

TRUE

54
Q

Give an example of an antiviral therapy

A

Vaccination

Cycle 3 - Infection (3 decks)

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