Textbook Chapter 3 Virus Classification: the world of viruses

Question 1

viruses are classified into families, genera, and species based on what?

Answer 1

characteristics of their genomes, capsids and replication strategies

Question 2

members of most not all virus families infect only organisms within what?

Answer 2

one of the 6 major divisions of life

Question 3

viruses with single stranded DNA genomes are what>

Answer 3

uniformly small and none has a lipid envelope

Question 4

viruses with double stranded DNA genomes are what?

Answer 4

widespread except for plants, and they can have genomes ranging from 5000 to more than a million base pairs

Question 5

viruses with positive strand RNA genomes are what?

Answer 5

predominant in the plant kingdom and common among vertebrates

Question 6

viruses with negative strand RNA genomes are what>

Answer 6

among the major infectious disease agents of humans, but are not found in prokaryotes

Question 7

viruses with double stranded RNA genomes can have up to how many different genome fragments?

Answer 7

12 different genome fragments, they are transcribed by a packaged RNA polymerase

Question 8

viruses with a reverse transcriptase are only known in what?

Answer 8

vertebrates and plants

Question 9

what are some characteristics of satellite viruses and viroids?

Answer 9

• they have very small genomes of from 250-1800 nucleotides

- are highly dependent on host cells or other viruses for packaging as well as replication

Question 10

what is the relationship for viruses with different genome types and replications strategies?

Answer 10

they may have originated independently at different times during the evolution of life