Virology

Question 1

what are the general characteristics to viruses?

Answer 1

• “non living” particles
• capsid and genome
• subcellular: smaller than cell
• intracellular: replicate within host cell, and use cell’s resources for own life cycle
• parasites: benefit from and harm host cells

Question 2

what do viruses NOT do?

Answer 2

• do NOT carry out metabolic processes
• do NOT reproduce independently of host cells
• do NOT contain nucleus, cytoplasm, and organelles

Question 3

describe viral structure

Answer 3

• very small
• genetic material
  (1) DNA or RNA
  (2) SS or DS
  (3) linear, segmented, circular
  (4) 2-1000 + genes

Question 4

can viral populations undergo evolution?

Answer 4

yes - constantly evolving

Question 5

capsid

Answer 5

• protein coat surrounding genome - in all viruses
• made up of capsomeres: capsid proteins
• determine morphology, involved in attachment to host cell

Question 6

envelopes

Answer 6

• phospholipid bilayer surrounding capsid - only some viruses
• acquired from host
• contains host and virus proteins

Question 7

what is the general cycle of replication?

Answer 7

• bind to host cell
• genome enters cell
• genome replication and gene expression
• assembly
• exit

Question 8

lytic cycle

Answer 8

• essentially the same as the general cycle
• host cell cell destroyes/lyses when viruses exit
• horizontal transmission
• the flu
• the spread of a virus from one thing to another

Question 9

lysogenic cycle

Answer 9

• viral genome gets replicated, but host cell is NOT destroyed
• vertical transmission
• Huntington’s disease
• transmission of virus from parent to offspring

Question 10

what are the phage types?

Answer 10

temperate phage and virulent phage

Question 11

temperate phage

Answer 11

capable of lytic and lysogenic replication (e.g. Phage Lambda)

Question 12

virulent phage

Answer 12

capable of lytic replication only (e.g. Phage T4)

Question 13

in what environmental conditions would lytic versus lysogenic replication be more favorable

Answer 13

• if there’s a lot of resources in the environment (lysogenic)
• in bad conditions (lack of resources) (lytic)