viruses

Question 1

what is a virus?

Answer 1

an infectious agent

Question 2

what are the living features of a virus?

Answer 2

can mutate and reproduce rapidly (only in a living host cell)

Question 3

what are the non-living features of a virus?

Answer 3

no cytoplasm or cellular organelles

does not carry out metabolism– replicates using host cell’s metabolic machinery

Question 4

viruses don’t grow and divide, instead ________

Answer 4

new viral components are synthesized and assembled within the infected host cell

Question 5

genome

Answer 5

the virus’s genetic material

Question 6

the genome can be ________ or _______, but never both

Answer 6

single stranded / double stranded

Question 7

the genome codes for the ___________

Answer 7

synthesis of viral components and viral enzymes for replication

Question 8

capsid

Answer 8

protein shell surrounding the genome

Question 9

what is the function of the capsid?

Answer 9

protect and introduce the genome into host cells

Question 10

what is a virus that is just a genome surrounded by a capsid called?

Answer 10

nucelocaspid or naked virus

Question 11

___________ project out from the capsid and binds the virus to a susceptible host

Answer 11

attachment proteins

Question 12

envelope

Answer 12

surrounding a polyhedral or helical nucleocaspid

Question 13

where does the envelope come from?

Answer 13

the host cell’s nuclear membrane, vacuolar membrane, or outer cytoplasmic membrane

Question 14

the envelope is usually of host cell origin, but the virus incorporates _________, which appear as ________ spikes

Answer 14

proteins of its own / gycoprotein

Question 15

what is the function of the glycoprotein spikes?

Answer 15

attaching the virus to receptors on susceptible host cells

Question 16

how does a virus cause disease?

Answer 16

uses another living host organism to reproduce

• there are so many viruses in the cell that it bursts and the viruses are free to move on to other cells in the host
• process repeats

Question 17

what are virus vaccines made of?

Answer 17

inactivated or attenuated viruses

Question 18

inactivated virus

Answer 18

does not replicate in a host cell

Question 19

attenuated viruses

Answer 19

genetically altered; cannot cause disease

Question 20

why are viral infections difficult to cure?

Answer 20

once inside the host, most substances that destroy the virus are also harmful to the host organism

Question 21

what were the first viral vaccinations for?

Answer 21

measles, mumps, rubella

Question 22

what are current viral vaccinations?

Answer 22

hepatitis A and B, chickenpox, smallpox, rabies

Question 23

antiviral drugs

Answer 23

interfere with the synthesis of viral nucleic acid or with the formation of viral caspids during replication

Question 24

antibiotics

Answer 24

no use for fighting viruses

Question 25

why are antibiotics not used in curing viral infections?

Answer 25

they attack the metabolism of a bacterial cell

-viruses do not have metabolism

Question 26

2 ways the body fights viruses

Answer 26

white blood cells

interferon

Question 27

white blood cells

Answer 27

engulf viruses in the blood and “digest” them

Question 28

interferon

Answer 28

a protein produced by cells when exposed to a virus

• binds the cell membranes of neighbouring cells
• interferes with the ability of a virus to enter the cell

Question 29

public health strategy

Answer 29

a coordinated effort to track, research, and reduce the incidence of specific health problems in a population

Question 30

vaccination

Answer 30

the process of giving a vaccine by mouth or injection to provide active immunity against a disease

Question 31

what are infectious diseased caused by?

Answer 31

pathogens (viruses, bacteria, fungi) entering the body

Question 32

what organ is the first line of defense that stops pathogens?

Answer 32

skin

Question 33

what does the immune system do to fight off pathogens?

Answer 33

send a flow of white blood cells (phagocytes) and dissolved substances to the site of the infection, causing inflammation

Question 34

what does bone marrow produce to help fight off pathogens?

Answer 34

white blood cells and disease-fighting molecules

Question 35

antigen

Answer 35

any material that the body considers foreign and triggers phagocytes

Question 36

antibodies

Answer 36

specialized proteins found in phagocytes