test 2 ch 16

Question 1

a small, infectious agent that is genetic information enclosed in a protein coat

Answer 1

virus

Question 2

two characteristics that all viruses share

Answer 2

genetic information and a protein coat

Question 3

surround the genetic material of a virus, the shape determines a virus’s overall form

Answer 3

protein coat (capsid)

Question 4

t or f: all viruses contain genetic material that carries the recipes for their proteins

Answer 4

true

Question 5

a lipid and protein-rich outer layer derived from the host cell’s membrane, proteins embedded in this outer layer help a virus invade a new host cell

Answer 5

viral envelope

Question 6

viruses that infect bacteria

Answer 6

bacteriophage

Question 7

the types of organisms or cells that a virus can infect

Answer 7

host range

Question 8

the host of a virus that acts as a continual source of viral infection for other host species (examples are wild birds, rodents, mosquitoes, raccoons)

Answer 8

viral reservoir

Question 9

why do biologists not consider viruses alive?

Answer 9

because they do not metabolize, respond to stimuli, or reproduce on their own

Question 10

t or f: viruses evolve by natural selection

Answer 10

true

Question 11

attachment (virus adheres to host cell receptor), penetration (virus enters cell), synthesis (multiple copies of the viral genome and proteins are produced by the host cell), assembly (the viral genetic info. is packaged in protein coat), release (new viruses leave host cell)

Answer 11

five steps of viral replication

Question 12

in this cycle a virus enters a bacterium, immediately replicates, and causes the host cell to birth as it releases a flood of new viruses; the newly released viruses infect other bacteria, repeating until all cells are dead

Answer 12

lytic cycle

Question 13

in this cycle, the genetic material of a virus is replicated along with the bacterial chromosome, but the cell lives and reproduces as usual, at some point the virus will revert to the other cycle

Answer 13

lysogenic cycle

Question 14

the DNA of a lysogenic bacteriophage that is inserted into the host chromosome

Answer 14

prophage

Question 15

describes the ability of a virus to damage its host during an infection, the more virulence the most likely to cause dire illness or death

Answer 15

virulence

Question 16

symptoms of a viral infection in animals using influenza as the example

Answer 16

cough and sore throat

Question 17

human immune system’s response to viral infection (influenza) that help to battle the virus

Answer 17

fever and body aches and fatigue

Question 18

viral genetic information inside an animal cell lies dormant; even as the infected host cell divides, new viruses are not produced bu the virus may be reactivated later (examples; cancer or papillomavirus ; or epstein-barr virus)

Answer 18

latent infection

Question 19

“teaches” the immune system to recognize one or more molecular components of a virus without actually exposing the person to the disease

Answer 19

vaccine

Question 20

how do viruses spread within a plant

Answer 20

viruses multiply at the initial site of infection, the killed plant cells often appear as small dead spots on the leaves; over time the viruses can spread from cell to cell through plasmodesmata, can also move throughout a plant by entering vascular tissues that distribute sap

Question 21

symptoms of viral infections in plants

Answer 21

streaking of some flower petals or blotchy, mottled leaves or abnormal growth

Question 22

how do plants fight viral infections

Answer 22

virus-infected cells may “commit suicide” before the infection has a chance to spread to neighboring cells or the plant may destroy the mRNA transcribed from viral genes

Question 23

a highly wound circle of RNA that lacks a protein coat; naked RNA that can infect a plant cell and can infect a plant by using its RNA to interfere with the plant’s ability to produce one or more essential proteins

Answer 23

viroid

Question 24

infectious particle made of protein; PrP is the normal membrane protein that can exist in multiple 3D shapes, at least one of which is abnormal and can cause disease

Answer 24

prion protein

Question 25

define prion

Answer 25

proteinaceous infectious particle

Question 26

diseases caused by prions

Answer 26

mad cow disease, kuru (associated with cannibalism in humans)