Microbiology: Viruses (physiology)

Question 1

What is a virus?

Answer 1

Single or double strand of nucleic acid covered by a protein coat or capsid

(Either DNA or RNA)

Question 2

What can the outer coating or envelope of a virus be made out of?

Answer 2

• protein
• lipid
  – Carbohydrate
• combination of these

Question 3

What are lipid enveloped viruses resistant to?

Answer 3

Disinfectants

Question 4

All living cells have a ______ that can infect them.

Answer 4

Virus

Question 5

What is a bacteriophage?

Answer 5

A virus that only infects bacteria

Question 6

________ are generally specific to one cell type.

Answer 6

Viruses

Question 7

Many envelope viruses have spikes on their surfaces called?

Answer 7

Antibody attachment sites

Question 8

What does an antibody attachment site allow a virus to do?

Answer 8

Allows the virus to mutate rapidly

Question 9

Example of a virus that can mutate rapidly

Answer 9

Influenza virus

Question 10

How do viruses fight off the antibodies the body produces?

Answer 10

By impaling the antibody and changing its antigen so the antibodies won’t recognize the virus anymore

Question 11

What are the different shapes of viruses?

Answer 11

1. Helical
2. Polyhedral
3. Complex
4. Enveloped

Question 12

What shape is a helical virus?

Answer 12

Rod shaped capsid

Question 13

What shape is a polyhedral virus?

Answer 13

Many sided figure

Question 14

What shape is a complex virus?

What virus has this shape?

Answer 14

• looks like a little alien
• has a diamond shaped “head”
• corkscrew “neck”
• little “legs”
• Bacteriophage

Question 15

What does an enveloped virus look like?

Answer 15

Envelope is flexible

Appears spherical

Question 16

Why is identifying the shape of a virus helpful?

Answer 16

Could help identify the virus

Question 17

How are viruses categorized?

Answer 17

Grouped by shape

Question 18

In the future how could we classify viruses?

Answer 18

1. according to single strand or double strand DNA or RNA

2. By type of cell infected

Question 19

Where can viruses multiply?

Answer 19

Inside a living cell

Question 20

Where can we grow viruses?

Answer 20

• In tissue or cell cultures
• Chick embryo
• Lawn of bacteria
• cancerous cells

Question 21

What type of cells grow poorly in cultures?

Answer 21

Animal cells

Will divide a few times then die

Question 22

Why can cancerous cells be used to grow viruses?

Answer 22

They have unregulated growth and are therefore “immortal”

Question 23

What are Hela cells?

Answer 23

Line of cancer cells from a patient that died in 1951

Still being used today

Question 24

How do viruses multiply via the lytic cycle?

Answer 24

1. Virus infects cell
2. Host DNA used to make viral DNA and viral proteins
3. Large number of viral pieces collect inside the host cell
4. Pieces assembled to form new viruses
5. Host cell is killed (lysed) and viruses are released into the environment

Question 25

How do viruses multiply via the lysogenic cycle?

Answer 25

1. Viral DNA or RNA it is spliced into host DNA 2. Host cell continues dividing, replicating viral DNA without expressing viral genes 3. Can exist for many years in the state - does not affect host cell 4. Viral DNA triggered to detach from host DNA 5. Cell goes through lytic cycle

Question 26

How can the lysogenic cycle of viral multiplication be used?

Answer 26

To insert missing genes or other genes for commercial products - genetic engineering

Question 27

How does a virus infect a prokaryotic cell?

Answer 27

1. Attachment 2. Penetration 3. Biosynthesis 4. Maturation (Assembly) 5. Release (lysis)

Question 28

How does a virus infect a eukaryotic cell?

Answer 28

1. Attachment 2. Endocytosis 3. Capsid dissolves 4. Free DNA/RNA it to nucleus 5. Biosynthesis 6. Maturation or assembly 7. Release or lysis