Viruses

Question 1

What is the basic structure of viruses?

Answer 1

A core of genetic material, a capsid (coat) and possibly an envelope

Question 2

How are viruses classified (3 points)?

Answer 2

1. Shape of the capsid [icosahedral (many planes) / helical (spiral) / complex (head, neck & tail)]
2. Envelope or not
3. Type of genetic material (DNA or RNA)

Question 3

What are the 4 ways that viruses reproduce?

Answer 3

1. Lytic (disintegration of the cell)
2. Lysogenic (phage DNA becomes incorporated into host genome, before lysing the cell to release newly made phages)
3. RNA viruses (RNA into nucleus of cell where it is transcribed by RNA polymerase > mutation likely due to error prone RNA polymerase > new viral particles leaves cell to infect others)
4. Reverse transcription (usually DNA > RNA > protein. Here, RNA > DNA > protein, so the virus is integrated into the actual DNA of the host and cannot be removed)

Question 4

How to viruses differ from other microbes (3 points)?

Answer 4

• Viruses are not ‘life’ - they cannot reproduce under their own steam, but need to enter a cell to do so.
• They are much smaller than bacteria (0.002 - 0.8um)
• They are very simple
  
  • no cell wall, no cellular activity
  • cannot reproduce by binary fission
  • only have up to 3 components

Question 5

Are viruses eukaryotic or prokaryotic?

Answer 5

Neither!

Question 6

Do viruses have DNA or RNA?

Answer 6

Yes, either DNA or RNA

Question 7

What are the 3 components that may make up a virus?

Answer 7

1. DNA / RNA
2. Capsid (protein coat)
3. Envelop (not on all viruses)

Question 8

What can a virus infect (3)?

Answer 8

Plants, bacteria, animals

Question 9

Viruses are ________ but their replication is _______

Answer 9

Simple, complex

Question 10

Name 6 common viral diseases

Answer 10

1. Influenza
2. Rubella
3. Varicella Zoster - Chicken pox/shingles
4. Hepatitis B
5. Human Papillomavirus
6. SARS CoV-2