viruses

Question 1

examples of viruses

Answer 1

bacteriophages
retroviruses

Question 2

retrovirus

Answer 2

RNA viruses that use reverse transcriptase to create double stranded DNA transcripts from single stranded RNA genome

Question 3

bacteriophage

Answer 3

viruses that infect bacterial cells

Question 4

bacteriophage structures

Answer 4

sheath - helps eject viral DNA into host
tail fibers - help with recognition and attachment

Question 5

viral nucleic acid (viral genome)

Answer 5

double or single stranded RNA or DNA

Question 6

prophage

Answer 6

viral genome integrated into bacterial genome

Question 7

provirus

Answer 7

viral genome integrated into eukaryotic genome

Question 8

capsid

Answer 8

protein coat enclosing and protecting nucleic acid

Question 9

viral envelope

Answer 9

outer membrane layer
composed of host cell membranes, other membrane proteins, and viral glycoproteins
- formed from infected host’s cell plasma membrane during the release of viral life cycle
- enveloped viruses are typically found in animals

Question 10

do viruses and bacteria both have nucleic acids

Answer 10

YES
shared commonality with living organisms

Question 11

viral infections in humans

Answer 11

disruption of host genes involved in cell replication by injection/integration of viral genome can lead to cancer cell development

Question 12

acute infection

Answer 12

rapid onset of symptoms and virion replication - brief and resolve in days

Question 13

chronic infection

Answer 13

initial period of high viral load > reduced to low once immune system controls infection > lasts several years to a lifetime

Question 14

latent infection

Answer 14

intermittent phases of high and low viral loads after initial acute&raquo_space; lasts years to a lifetime

Question 15

slow progressing infection

Answer 15

seems dormant after initial viral load but progresses (viral replication) years later

Question 16

bacterial defense against viruses

Answer 16

• cell surface mutations prevent phages from identifying bacterial surface proteins
• if phage DNA is inside the cell restriction enzymes cut at specific recognized sequences to prevent replication
• CRISPR-Cas system

Question 17

CRISPR Cas

Answer 17

internal defense of bacteria that recognizes and cuts out viral genomes
used in biotechnology for genome editing

Question 18

viral outbreaks (2 types)

Answer 18

epidemic - large population
pandemic - global impact

Question 19

vaccines

Answer 19

weakened agents that mimic disease-causing organism to stimulate immune system

Question 20

viral modifications can be… (2)

Answer 20

antigenic shift
antigenic drift

Question 21

antigenic shift

Answer 21

viruses mix genes to increase host ranges
difficult to treat

Question 22

antigenic drift

Answer 22

minor changes in viruses allow for infection of same host species

Question 23

prions

Answer 23

infectious misfolded proteins that cause other proteins to misfold into the prion form

Question 24

viroids

Answer 24

single stranded RNA molecules that infect plants

Question 25

viral life cycle + methods of replication for bacteriphage

Answer 25

1. attachment
2. entry
3. uncoating
4. synthesis/replication
5. self-assembly
6. release

Question 26

1. attachment

Answer 26

between host cell and specific viral surface proteins
- virus has host ranges (set of species it can infect)
- can be limited in type of tissue

Question 27

2. entry
   depends on type and host cell

Answer 27

bacteriophage inject genome into bacterial host cell using protein tail
enveloped viruses will fuse their viral envelopes with host membrane and other viruses are taken in via endocytosis

Question 28

3. uncoating

Answer 28

once inside host viral genome is exposed via breakdown of viral capsid

Question 29

4. synthesis/replication

Answer 29

virus replicates its genome and viral proteins
requires host’s nucleotides, enzymes, and ribosomes

Question 30

5. self-assembly

Answer 30

viral components spontaneously assemble into new complete viral particles called virions

Question 31

6. release

Answer 31

where viral shedding allows newly replicated viral particles to leave host
via budding, apoptosis, exocytosis

Question 32

lytic cycle

Answer 32

bacteriophage infects and injects genome into host cell then transcribes it into viral particles that are assembled into new viruses - host cell bursts and is destroyed while virus replicates and attacks other cells
active process where phage replicates in host cell

Question 33

lysogenic cycle

Answer 33

passive process - bacteriophage integrates into host genome without actively creating new viral particles
every time host cell replicates viral genome replicated as well
- viral genome may later be triggered to enter lytic cycle to produce new viral particles