Chapter 18

Question 1

what is a virus?

Answer 1

an infectious particle made only of a strand of DNA or RNA surrounded by a protein coat

Question 2

describe the structure of a virus?

Answer 2

nucleic acid core and protein coat

Question 3

why do viruses not have scientific names?

Answer 3

they are unliving

Question 4

what is a disease causing agent called?

Answer 4

pathogen

Question 5

what are four key characteristics that all living things share?

Answer 5

abilities to reproduce, use nutrients and energy, grow and develop, and respond to environments

Question 6

what are viroids?

Answer 6

infectious particles that cause disease in PLANTS

Question 7

what are viroids made of?

Answer 7

single stranded RNA and a protein coat

Question 8

how are viroids transported?

Answer 8

through seeds and pollen

Question 9

what is a prion?

Answer 9

an infectious particle made only of proteins that can cause other proteins to fold incorrectly

Question 10

what happens when proteins are folded incorrectly?

Answer 10

they do not function properly

Question 11

what is unusual about prions?

Answer 11

they are infectious yet contain no genetic material

Question 12

what disease do prions play a part in?

Answer 12

mad cow disease/bse

Question 13

what is the unifying characteristic of protists, fungi, plants, and animals that are all in the domain archaea?

Answer 13

they all have a nucleus

Question 14

how do humans get bse?

Answer 14

eating meat from animals infected from the disease

Question 15

name the domain each kingdom is in?

Answer 15

bacteria-bacteria
fungi protest animal- eukarea
archae- archae

Question 16

diseases brought on by prions are always what?

Answer 16

fatal

Question 17

why are these prion diseases always deadly?

Answer 17

the body has no immune response against a protein

Question 18

what is the common factor between viruses, bacteria, viroids, and prions?

Answer 18

they can all cause infection

Question 19

true or false: viruses are all the same shape and enter host cells the same way

Answer 19

false: viruses differ in shape and in ways of entering host cells

Question 20

what is a virion?

Answer 20

a single, viral particle made up of genetic material surrounded by a capsid

Question 21

what is a capsid?

Answer 21

the protein shell that surrounds virions; sometimes surrounded by a lipid envelope that is a protective outer coat of virus, from which spiky structures of proteins and sugars stick out

Question 22

when and only when can viruses reproduce?

Answer 22

after they have attached to a host cell

Question 23

what is an obvious trait of some viruses that can be used for identification?

Answer 23

spikes

Question 24

how does a virus attach to a host cell?

Answer 24

virus identifies its host by fitting its surface proteins to receptor molecules on the surface of a host cell, like a key fitting a lock

Question 25

what type of virus is influenza?

Answer 25

enveloped virus- has spikes

Question 26

what type of virus is rabies?

Answer 26

helical virus- long, narrow, coiled shape called a helix; has a lipid envelope

Question 27

what type of virus is foot-and-mouth disease?

Answer 27

polyhedral virus- many sided

Question 28

true or false: a virus can have both RNA and DNA

Answer 28

false: a virus can have either DNA or RNA, but never both

Question 29

what are viruses that infect bacteria called?

Answer 29

bacteriophages

Question 30

what is one way viruses enter a host cell?

Answer 30

endocytosis

Question 31

once inside the cell, what do viruses target?

Answer 31

the cell’s nucleus