Viruses & Prions

Question 1

________ are infectious, acellular particles that must invade cells to replicate

Answer 1

Viruses

Question 2

________ is a complete infective form of a virus outside a host cell with a core of RNA or DNA plus a capsid

Answer 2

Virion

Question 3

Viral genome can be single- or double-stranded
▪ _____viral genomes – circular or linear; often double stranded
▪ ____ viral genomes – linear or segmented; often single stranded

Answer 3

DNA, RNA

Question 4

________ surround the viral genome
▪ Made of repeating units called_________
▪ Types include helical, complex, and icosahedral

Answer 4

Capsid, Capsomeres

Question 5

________ viruses do not have an envelope

Answer 5

Naked

Question 6

Many viruses have spikes (____) that help them infect a host cell

Answer 6

peplomers

Question 7

RNA viruses tend to mutate _____ frequently than DNA viruses

Answer 7

more

Question 8

Occurs due to small mutations in antigen-coding genes;
Responsible for seasonal influenza variations

Answer 8

Antigenic drift

Question 9

Occurs when two different strains infect the same cell and undergo
reassortment to make a new virus strain; Often responsible for pandemic strains

Answer 9

Antigenic shift

Question 10

Mainly classified by the type of ____________, capsid symmetry, presence/absence of an envelope and genome architecture (e.g.,
ssDNA, ssRNA

Answer 10

Nucleic Acid Present (DNA or RNA)

Question 11

What do viruses use from a host to build new virions (4)

Answer 11

Cell’s energy
Enzymes
Organelles
Molecular building blocks

Question 12

Viruses that infect bacteria

Answer 12

Bacteriophages

Question 13

Bacteriophages perform _________ pathways

Answer 13

lytic or lysogenic replication

Question 14

Involves attachment, penetration, replication, assembly and release from the host cell; This type of pathway kills the host cell

Answer 14

Lytic pathways

Question 15

Involves the insertion of the phage genome into the host’s chromosome to form a prophage; Through phage conversion, prophages confer new properties onto a host bacterium; At any point, the prophage can excise itself from the host genome to continue into the lytic pathway

Answer 15

Lysogenic replication

Question 16

Name animal virus replication 6 steps

Answer 16

• Attachment – often aided by spikes or other capsid proteins
• Penetration – naked viruses mainly enter by endocytosis while enveloped
  viruses use membrane fusion or endocytosis
• Uncoating
• Replication
• Assembly
• Release – enveloped viruses bud out of the host cells while naked viruses lyse the host cell

Question 17

These ____ effects can change cell functions or even destroy the cell

Answer 17

Cytopathic

Question 18

Infectious proteins that cause transmissible spongiform encephalopathies

Answer 18

Prions