Biological Diversity: Viruses

Question 1

Viruses

Answer 1

Non living infectious particles capable of infecting other cells, replicating inside of them and continuing to infect more cells

Question 2

Types of viruses

Answer 2

Bacteriophages
Retroviruses

Question 3

Retroviruses

Answer 3

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

Question 4

Virus components

Answer 4

Nucleic acid
Capsid
Viral envelope

Question 5

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

Question 10

Bacteriophage

Answer 10

Viruses that infect bacterial cells

Question 11

Additional structures of bacteriophages

Answer 11

Sheath
Tail fibers

Question 12

Sheath of bacteriophage

Answer 12

Helps eject viral DNA into host

Question 13

Tail fibers

Answer 13

Help with recoginition and attachment

Question 14

Viral infections in humans

Answer 14

Acute
Chronic
Latent
Slow progressing

Question 15

Acute infection

Answer 15

Rapid onset of symptoms and virion replication; brief and resolved in days

Question 16

Chronic infection

Answer 16

Initial period of high viral load; reduced to low once immune system controls infection
Lasts several years to lifetime

Question 17

Latent infection

Answer 17

Intermittent phases of high and low viral loads after initial acute
Lasts years to a lifetime

Question 18

Slow progressing

Answer 18

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

Question 19

Defense against viruses

Answer 19

Cell surface mutations
Restriction enzymes
CRISPR- Cas system

Question 20

Cell surface mutations

Answer 20

Prevents phages from identifying bacterial surface proteins

Question 21

Restriction enzymes

Answer 21

Cut a specific recognized sequences to prevent replication if phage is inside the cell

Question 22

CRISPR- Cas System

Answer 22

Internal defense of bacteria that recognizes and cuts out viral genomes

Question 23

Viral outbreaks

Epidemics

Answer 23

Large population

Question 24

Pandemic

Answer 24

Global impact

Question 25

Vaccines

Answer 25

Weakened agents that mimic disease causing organism to stimulate immune system

Question 26

# Viral modifications Antigenic shift

Answer 26

Viruses mix genes to increase host ranges, difficult to treat

Question 27

Antigenic drift

Answer 27

Minor changes in viruses allow for infection of same host species

Question 28

# Infectious particles Prions

Answer 28

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

Question 29

Viroids

Answer 29

Single stranded RNA molecules that infect plants

Question 30

Viral life cycle (bacteriophage)

Answer 30

Attachment, entry, uncoating, synthesis, self assembly, release

Question 31

lytic cycle

Answer 31

Virus injetcts genetic material into host cell, hijacks cell machinery to produce more virus New virus **erupts** from the host cell membrane and kills cell in process

Question 32

Lysogenic cycle

Answer 32

Virus hides out in a host's genome, viral DNA is incorporated into the DNA of the host cell After dormant virus recieves a certain signal from the environment it undergoes the lytic cell and kills the cell

Question 33

Provirus

Answer 33

dormant stage

Question 34

Attachment in viral life cycle

Answer 34

Between host cell and specific viral surface proteins

Question 35

Entry stage of life cycle

Answer 35

Bacteriophage inject genome into bactieral host cell using protein tail; enveloped viruses will fuse their viral envelopes with host membrane, and other viruses are taken in via **endocytosis**

Question 36

Uncoating

Answer 36

Once inside host, viral genome is exposed via breakdown of viral capsid

Question 37

Synthesis/ Replication

Answer 37

Virus replicated its genome and viral proteins; requires host's nucleotides, enzymes, and ribosomes

Question 38

Self assembly

Answer 38

Viral components spontaneously assemble into new complete viral particles called **virions**

Question 39

Release

Answer 39

Where viral shedding allows newly replicated viral particles to leave host (via budding, apoptosis, exocytosis)