lecture 31 - viruses Flashcards

1
Q

Are viruses cellular or acellular organisms?

A

Acellular

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2
Q

Why can’t viruses survive without a host?

A

They have no metabolic abilities of their own and rely on the bio synthetic machinery of infected cells to multiply

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3
Q

What is an obligate intracellular parasite?

A

An organism, such as a virus, that rely on a suitable host to complete their life cycle.

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4
Q

What are the 2 essential components of a virus?

A

Genetic material, capsid

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5
Q

What is a feature of viruses that only certain types have?

A

An envelope of lipids that surrounds the protein coat/capsid

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6
Q

What is a viral capsid?

A

A protein coat that surrounds, and protects the genetic material of, a virus.

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7
Q

What are viral capsids composed of?

A

Multiple units of protein building blocks called. capsomers that form a precise pattern around the virus’s nucleic acid.

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8
Q

What are 3 types of capsid symmetry?

A

Helical, icosahedral, complex

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9
Q

What is the structure of a helical virus?

A

Capsomeres coil around the nucleic acid into a tightly bound helix that resembles a tube.

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10
Q

What is the structure of an icosahedral virus?

A

The capsid is an icosahedral shape - a 20 faced polygon made up of equilateral triangles

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11
Q

What is the structure of a complex virus?

A

Contains components with different symmetries - e.g. an icosahedral head with helical tails.

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12
Q

How is the viral genome stored?

A

Nucleic acid - DNA or RNA - contained within the viral capsid

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13
Q

Do viruses have DNA or RNA?

A

Both or either

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14
Q

What are the possible structures of the DNA and RNA found in viruses?

A

Linear, circular, segmented

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15
Q

Is DNA and RNA double or single stranded in viruses?

A

Both ds and ss RNA and DNA are found in viruses.

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16
Q

What type of virus infects a host via the lytic cycle?

A

Bacteriophages

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17
Q

What are bacteriophages?

A

Viruses that infect and then replicate inside bacteria.

18
Q

What is the name of the process in which bacteriophages infect bacteria?

A

The lytic cycle

19
Q

What are 6 phases off the lytic cycle?

A

Attach, Penetrate, Uncoat, Genome replication & gene expression, Assembly, Release

20
Q

What occurs during the attachment stage of the lytic cycle?

A

Phage attaches to the surface of a bacterial cell using its tail fibres

21
Q

What occurs during the penetration stage of the lytic cycle?

A

Viral DNA is injected into the bacterial cell

22
Q

What occurs during the uncoating stage of the lytic cycle?

A

The virus phage sheds its capsid, leaving the viral genome exposed

23
Q

What occurs during the gene replication & expression stage of the lytic cycle?

A

DNA/RNA is replicated, transcripted and translated, and phage proteins/components are made.

24
Q

What occurs during the assembly stage of the lytic cycle?

A

Several new phage particles are assembled from the phage components manufactured during gene expression.

25
Q

What occurs during the release stage of the lytic cycle?

A

The bacterial cell lyses/ruptures, releasing the newly made bacteriophages.

26
Q

What is the structure of a SARS-CoV-2 virus?

A

An enveloped virus, with linear non-segment ssRNA

27
Q

What type of nucleic acid does the SARS-CoV-2 virus have?

A

single stranded RNA

28
Q

What is the function of the spike on a SARS-CoV-2 virus?

A

Cell entry and attachment.

29
Q

What part of a SARS-CoV-2 virus is targeted by vaccines?

A

The spike - to neutralise immunity

30
Q

How do spike viruses bind to the surface of cells?

A

Receptor Binding Domain (RBD) on spike binds to an ACE2 receptor protein on the cell surface

31
Q

What part of a virus spike protein binds with the cell surface of target cells?

A

Receptor binding domain (RBD)

32
Q

What part of a cell surface will spike proteins bind to in order for a virus to infect the cell?

A

ACE2 receptor

33
Q

Where do SARS-CoV-2 viruses replicate?

A

In the cytoplasm of host cells that they infect

34
Q

What is HIV?

A

A virus - Human Immunodeficiency Virus

35
Q

What disease does HIV cause?

A

AIDS - Acquired Immunodeficiency Syndrome

36
Q

What is the structure of the genetic material of an HIV virus?

A

ssRNA

37
Q

What is a provirus?

A

A component of a viral DNA/RNA that has been converted to dsDNA by reverse transcriptase and that is incorporated into the nucleus of a host cell for expression.

38
Q

What enzyme is used to incorporate the genetic material of a virus into the host genome?

A

Viral integrase

39
Q

What is a prophage?

A

The genetic material of a bacteriophage that is incorporated into a bacterial genome and then produce proteins if transcripted and translated.

40
Q

Are viruses visible under a light microscope?

A

No - only visible with an electron microscope