An Intro to Viruses

Question 1

acellular

Answer 1

not consisting of cells

Question 2

obligate intracellular parasites

Answer 2

inert and incapable of reproduction outside of cells

Question 3

bacteriophage

Answer 3

complex viruses capable of infecting bacteria

Question 4

host range

Answer 4

spectrum of host cells (both the kind of organism and the type of cell) that a particular pathogen can infect

Question 5

restriction enzymes

Answer 5

proteins that recognize specific DNA sequences and cleave them at or near the recognition site

Question 6

CRISPR

Answer 6

a gene modification system

Question 7

virome

Answer 7

collective viral community present in a specific environment or within a particular host organism

Question 8

oncogenic

Answer 8

have some involvement in the development of transformed/cancerous cells

Question 9

virion

Answer 9

mature virus particle

Question 10

nucleocapsid

Answer 10

nucleic acids surrounded by a protein coat

Question 11

nucleic acids

Answer 11

DNA or RNA

Question 12

capsid

Answer 12

protein coat that protects viral nucliec acids

Question 13

protomer

Answer 13

protein subunits that make up the capsid

Question 14

capsomere

Answer 14

made of protomers and determines shape of the virus

Question 15

helical capsid

Answer 15

protomers form a rigid hollow tube

Question 16

icosahedral capsid

Answer 16

regular polyhedron with 20 equilateral triangular faces and 12 vertices

Question 17

Capsid of Complex Symmetry

Answer 17

not helical or icosahedral

Question 18

Capsid of Complex Symmetry

poxviruses

Answer 18

largest animal viruses with ovoid to brick shap exteriors

Question 19

Capsid of Complex Symmetry

complex phage

Answer 19

binal symmetry with icosahedral head and helical tail

Question 20

Naked capsid virus
- Advantage?

Answer 20

virion includes only a nucleocapsid
- remain infectious outside of the body for longer compared to eveloped viruses

Question 21

enveloped virus
- disadvantage?

Answer 21

virion includes nucleocapsid and envelope
- need fluid for transmission

Question 22

virus envelope

Answer 22

lipids and carbohydrats acquired from host membrane and envelope proteins called spikes which are encoded by the virus

Question 23

spikes
- function?

Answer 23

envelope proteins
- host cell attachment
- antigenic
- enzyme function

Question 24

Virion Enzymes for Infection//Biosynthesis

lysozyme

Answer 24

• encoded by phage
• makes hole to allow for entry of phage nucleic acids
• produced at the end of biosynthesis to lyse the host bacterial cell

Question 25

# Virion Enzymes for Infection//Biosynthesis neuroaminidase

Answer 25

- spike protein encoded by influenze that has enzymatic activity - supports separation of the envelope from the host cell during release

Question 26

# Virion Enzymes for Infection//Biosynthesis Nucleic acid polymerase

Answer 26

support replication of viral nucleic acids that host cell cannot replicate

Question 27

# Virion Enzymes for Infection//Biosynthesis RNA replicase

Answer 27

RNA-dependent RNA polymerase encoded by RNA viruses

Question 28

# Virion Enzymes for Infection//Biosynthesis reverse transcriptase

Answer 28

converts retrovirus RNA into DNA

Question 29

# Virus Classification The Baltimore Scheme

Answer 29

- developed by David Baltimore - groups viruses based on relationship between their genomes and mRNA - DOES NOT describe relationship between viruses

Question 30

# Virus Classification International Committee on Taxonomy of Viruses (ICTV)

Answer 30

- uses host range, structural morphology, replication cycle, nucleic acid sequence and pathogenicity to classify

Question 31

# Steps in the Viral Replication Cycle Eclipse Phase

Answer 31

time when no virions are detected in or outside of cells (genome is being replicated and protein synthesized)

Question 32

# Steps in the Viral Replication Cycle Maturation

Answer 32

packaging of nucleic acids in capsids (first virion detected)

Question 33

# Steps in the Viral Replication Cycle burst size

Answer 33

number of virions released, increases during maturation and then plateaus

Question 34

# Steps in the Viral Replication Cycle Latent period

Answer 34

eclipse + maturation phases

Question 35

# Steps in the Viral Replication Cycle attachment

Answer 35

ligand on the virion attaches to a receptor on the host cell

Question 36

# Steps in the Viral Replication Cycle entry

Answer 36

genome alone or entire nucleocapsid or virion enters the host cell

Question 37

# Steps in the Viral Replication Cycle synthesis

Answer 37

viral nucleic acids are synthesized/replicated and viral proteins are syntehsized

Question 38

# Steps in the Viral Replication Cycle assembly

Answer 38

nucleic acids are packaged in the capsid

Question 39

# Steps in the Viral Replication Cycle release

Answer 39

host cell lysis or budding occurs