Lecture 5: viruses pt. 1

Question 1

What two major things are different about viruses, compared to other microbes?

Answer 1

1. Are not cells
2. are not living

Question 2

Viruses are considered _____ _______ parasites.

Answer 2

Obligate Intracellular

Question 3

How do viruses function outside host cells?

• Outside host cell?

Answer 3

Are inactive outside

• Only active in host cell

Question 4

What are the components of viruses from outside to inside?

How common are these components?

Answer 4

1. Envelope (on some)
2. Capsid (on all
3. Nucleic Acid (in all)
4. 1 or 2 enzymes (sometimes)

Question 5

Fully formed virus, able to establish infection in host:

Answer 5

Virion

Question 6

• Viruses that have viral envelopes are called:
• Viruses without envelopes are called:

Answer 6

• Enveloped
• Naked

Question 7

What are most viral envelopes made from?

Answer 7

The host cell’s membrane.

Question 8

• What projections do viral envelopes contain on the outside?
• What is their purpose?

Answer 8

• Spikes
• Attachment and Entry

Question 9

• What is the layer that sourronds the nucleic acids of Viruses?
• What is it made of?

Answer 9

• Capsid
• Capsomeres

Question 10

What are the 3 types of capsid shapes?

Answer 10

1. Helical (rod shaped)
2. Icosahedral (geometric)
3. Complex

Question 11

What types of nucleic acids can viruses have?

Answer 11

DNA or RNA (but not both)

Question 12

What variations can virus genomes come in (5 types)

Answer 12

1. Double stranded
2. Single stranded
3. Segmented (RNA only)
4. Positive sense (RNA only)
5. Negative sense (RNA only)

Question 13

What is the life cycle of viruses? (6 steps)

Answer 13

1. Attachment
2. Entry
3. Uncoating
4. Replication
5. Assembly
6. Release

Question 14

How do viruses attach (enveloped and naked)?

Answer 14

• Enveloped viruses use spikes
• Naked viruses use campsomeres

Question 15

What is the host range of a virus?

Give the types.

Answer 15

What species/cell type a virus can invade

1. Narrow
   
   1. Specific cells only
2. Moderate
   
   1. Specific specie
3. Broad
   
   1. Can infect many species

Question 16

Host cells that do not have certain receptor that viruses can infect, it is ____

Answer 16

Resistant

Question 17

a. What are the types of way a enveloped virus can enter cells?

b. Naked viruses?

Answer 17

a. 1) Fuses with host membrane
2) Endoctosis
b. 1) endocytosis

Question 18

What do:

1) Early
2) Middle
3) Late genes

do?

Answer 18

1) Take over host cell machinery
2) Replicate viral genome
3) Include capsid proteins

Question 19

What part of the enveloped virus escapes when entering by endocytosis?

Answer 19

Nucleocapsid

Question 20

What part of naked viruses escapes when entering by endocytosis?

Answer 20

Nucleic acid

Question 21

Name the steps that dsDNA goes through when infecting a cell.

Answer 21

1. Must enter nucleus
2. Makes more dsDNA and mRNA
3. mRNA travels to cytoplasm to make viral proteins
4. Uses host DNA polymerase (to make more DNA)

Question 22

What is the difference between how Single Stranded DNA enter/ replicate?

Answer 22

Does the same thing except

must become dsDNA first after entering the nucleus.