Lecture 1

Question 1

What is a virus?

Answer 1

Obligate intracellular parasite that requires host energy & replicates by assembly

Question 2

What 2 things do viruses require?

Answer 2

1. Energy from host
2. Host ribosomes to translate viral mRNA to protein

Question 3

True or false: Viruses divide

Answer 3

False
Viruses do not divide they assemble from parts made within the cell

Question 4

Ways that viruses differ from bacteria and eukaryotic cells include:

Answer 4

1. All viruses replicate by assembly of viral components rather than by division.
2. Viral genomes can be RNA, whereas all bacterial and eukaryotic cells have DNA genomes.
3. All viruses require host ribosomes for mRNA translation.

Question 5

Are all viruses pathogenic?

Answer 5

No, we have been infected by many viruses we never knew

Question 6

What is significant about smallpox

Answer 6

-Killed lots of people
-Led to the first vaccine
-Eradicated

Question 7

What is significant about HIV

Answer 7

HIV can jump from chimps to humans
-causes AIDS

Question 8

What are some things we learned from viruses

Answer 8

-Viruses break central Dogma by using reverse transcriptase
-Viruses can cause cancer if they have Sarcoma gene–>HPV 1st vaccine that prevents cancer
-bacteriophage was studied to learn about genomes
-CRISPR Cas systems–> virus immune defense

Question 9

True or false: One physical virus equals one infectious virus

Answer 9

False
One physical virus does not equal one infectious virus

Question 10

What does electron microscopy detect

Answer 10

-Viral particles
-capsid
-physical properties (size, shape)
-can measure viruses that cant be cultured
-DOES NOT measure infectious virus particles

Question 11

How to detect viral products

Answer 11

Viral protein detection using antibodies
-Western blot
-Immunofluorescence
-ELISA

Question 12

How to detect nucleic acid?

Answer 12

Polymerase chain reaction (PCR)
-fast
-does not need full virus to detect
-does not measure actual infectious particles

Question 13

What does a plaque assay measure?

Answer 13

-true infectious units

Question 14

What checks for if viruses can cause red blood cells to agglutinate

Answer 14

Hemagglutination assay
-can work with non infectious particles
-not accurate since it depends on interpretation

Question 15

What checks if a virus was once there?

Answer 15

Measurement of antibody titer
-viruses dont need to be present
-can see if someone can do an immune response