Lec 1 - Intro

Question 1

who first observed virusesand when

Answer 1

1800s
(around 200 yrs after first microorganisms were discovered)
by Ivanovsky

Tobacco mosaic virus

Question 2

how did Ivanovsky discover this

Answer 2

used 0.2 micrometer filters
put ground up leave tissue through it
and found the filtered liquid had the disease agent and not the concentrated filtrate
(so it was small enough to pass through)

Question 3

What did Beijernick then discovered after Ivanovsky

Answer 3

that the filterable agent was a distinct microbe and not a tiny bacteria

Question 4

What was the first animal virus discovered

Answer 4

foot and mouth
found that the pathogen can only replicate in the host, and it wasnt a toxin but something that could replicate

Question 5

what must all viruses do regardless of the structure

Answer 5

make mRNA

Question 6

what is the baltimore classifcation system

Answer 6

divides viruses into 7 genome types
e.g. + DNA, -RNA etc.
- Takes into account the steps needed for the virus’s genome to be converrted to mRNA

Question 7

examples of viruses w DNA genomes

Answer 7

circovirus
pandoravirus
megavirus
mimivirus
herpes virus

Question 8

why is genome smaller in
RNA viruses

Answer 8

• RNA is more susceptible to nuclease attack
  segmenting the RNA
• no error correction enzyme
  overcomes this problem

Question 9

if there are no fossil records, then how do we know that viruses are old

Answer 9

• isolated a virus from a deep thermal vent
• sequenced the genome
  and found similarities to both animal and bacterial viruses
• so there is a common ancestor that precedes them both

Question 10

what are the 3 hypothesis

Answer 10

• escape/progressive hypothesis
• reduction or regressive hypothesis
• virus-first hypothesis