chapter 19: viruses

Question 1

are viruses living or non-living?

Answer 1

no, but not lifeless

Question 2

can viruses reproduce and carry out metabolic activities outside of a host cell?

Answer 2

no

Question 3

characteristics of viruses

Answer 3

can infect every type of cell
can’t exist independently of host cell
can’t multiply unless they invade a host cell

Question 4

are viruses cells?

Answer 4

no

Question 5

viruses are also referred to as

Answer 5

infectious particles
obligate intracellular parasites

Question 6

capsid

Answer 6

protein shell enclosing viral genome

Question 7

capsomeres

Answer 7

protein subunits that cause viruses to have different shapes

Question 8

some viruses have a membranous _

Answer 8

envelope

Question 9

all viruses have

Answer 9

genetic material
protein shell or coat

Question 10

genetic material that makes up viral genomes

Answer 10

double or single stranded DNA (DNA virus)
double or single stranded RNA (RNA virus)

Question 11

the protein shell/coat is comprised on

Answer 11

capsomeres

Question 12

2 components of membranous envelope

Answer 12

membrane
glycoproteins

Question 13

the host of the DNA provides

Answer 13

nucleotides
enzymes
ribosomes
tRNA
amino acids
ATP
etc

Question 14

DNA viruses use host’s

Answer 14

DNA polymerase

Question 15

RNA viruses use their own _ that can use RNA as a _

Answer 15

polymerases
template

Question 16

viruses usually infect

Answer 16

a specific host cell
some only infect a single species or cells of particular tissues or have a broad range

Question 17

viruses can be compared to

Answer 17

“lock and key”
viral surface proteins + receptors on outside of host cells

Question 18

the CRISPR-Cas9 system is

Answer 18

a bacterial “immune system”

Question 19

CRISPR stands for

Answer 19

Clustered Regularly Interspaced Short Palindromic Repeats

Question 20

can phages infect the same cell twice?/

Answer 20

no

Question 21

in CRISPR, each “spacer” sequence between the repeats corresponds to

Answer 21

DNA from a phage that infected the cell

Question 22

CRISPR-associated (Cas) proteins

Answer 22

particular nuclease proteins that interact with the CRISPR region

Question 23

CRISPR-Cas9 system steps

Answer 23

1. Cas9-guide RNA complex is formed when guide RNA with a complementary sequence that can bind to a target gene attaches to active site of Cas9 protein
2. guide RNA cuts part of the target gene
3. normal gene is used as a template to repair enzymes
4. cut gene is used to “knock out” target gene to study its normal function
5. if target gene has a mutation, it can be repaired