Viruses Flashcards

1
Q

Where does the word virus come from?

A

It comes from the latin word meaning poison

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2
Q

What kingdom to viruses belong to?

A

They don’t belong to any kingdom as they are not classified as living

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3
Q

What do viruses do that make them non living?

A
  • they do not carry out their own metabolic functions
  • they don’t eat
  • they can’t reproduce by themselves
  • it must be in a cell in order to reproduce
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4
Q

How big are viruses

A

range from 20 to 250 nm

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5
Q

Virus definition

A

Viruses are very small infectious particles consisting of nucleic acid enclosed in a protein coat or a capsid and in some cases and membranous envelope

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6
Q

Describe viral acid or genome

A

It can be either double or single-stranded DNA or double or single strand RNA

Viruses can be classified as either DNA or RNA viruses

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7
Q

What ‘protects’ the virus?

A

Capsids protect the genome. A capsid is a protein shell

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8
Q

Nucleocapsid or naked viruses

A

this is a virus that consists of only a capsid

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9
Q

How are viruses classified?

A

classified by shape based on the capsid - the capsid can have various structures.

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10
Q

Alternative name for a bacteriophage

A

Phage

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11
Q

Bacteriophage

A

a virus that infects bacteria

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12
Q

Which virus have the most complex capsid?

A

Bacteriophages

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13
Q

Which type of virus is most well studied?

A

Bacteriophages

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14
Q

Viruses infecting animals have these things that help them infect.

A

membranous envelopes that surround them

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15
Q

Where does viral envelope come from?

A

It comes from the host cell’s membrane.

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16
Q

What is the viral envelope made out of?

A

It is made up of both viral and host cell components.

17
Q

What is the process that creates viral envelopes called?

A

Budding

18
Q

Host Range

A

The types of cells a virus can infect.

For example:
- polio -> only human nerve and intestinal cells
- bacteriophages -> only infect bacteria
- rabies ->infect many mammalian species and even birds in the lab

19
Q

Where can viruses reproduce?

A

Viruses can only reproduce within a host cell

20
Q

Describe the process of viral reproduction

A
  1. Entry and uncaoting - The capsid is removed as the nucleic acid enters the cell
  2. Replication - copies of the nucleic acid are made
  3. Transcription and manufacture - viral proteins are made from the viral DNA
  4. Self-assembly - viral nucleic acid, and viral proteins make new viruses that exit from the host cell
21
Q

Name the two possible reproductive cycles viruses use.

A

The lytic cycle and lysogenic cycle.

22
Q

Give examples of viruses that use the Lytic cell.

A

Ebola, influenza

23
Q

Describe the Lytic cycle.

A

The virus reproduces in the cell as more viruses are made it breaks open the host cell, resulting in the death of host cell.

24
Q

What you call a virus that reproduces using the Lytic cycle.

A

Virulent

25
Q

Give examples of viruses that use the lysogenic cycle

A

HIV, herpes, chicken pox.

26
Q

Describe the Lysogenic cycle.

A
  • copies the viral genome without destroying the host cell
  • viral DNA incorporates into host cell’s chromosome
  • the host cell passes the viral DNA to the daughter cell every time it divides
  • an environmental signal can trigger the virus genome to exit the host’s chromosome and switch into lytic mode
27
Q

provirus

A

the viral DNA that becomes part of the host cell’s chromosome

28
Q

Temperate viruses

A

viruses that use both the lytic and lysogenic cycle.

29
Q

retroviruses

A

RNA genome viruses

30
Q

Glycoprotein

A

the thing sticking out of a virus

31
Q

Describe the steps of the lytic cycle

A
  1. Attachment - a virus recognizes and attaches to a host cell when one of its proteins interlocks with a receptor on the host cell’s plasma membrane
  2. Entry of phage DNA and degradation of host DNA
  3. Synthesis of viral genomes and proteins. The host cell uses its own enzymes, raw materials and energy to make copies of viral genomes and viral proteins.
  4. Assembly - new virus particles are made
  5. Release - this can occur between 20-40 minutes after attachment and release 50 - 200 viruses
32
Q

How do retroviruses work?

A

They use an enzyme called transcriptase to copy their RNA genome into DNA - the double stranded viral DNA is then taken into the host cell’s chromosome and becomes a provirus