Chapter 19: Viruses

Question 1

An infectious particle consisting of genes packaged in a protein coat

Answer 1

Virus

Question 2

T/F: viruses are more complex in structure than prokaryotic cells

Answer 2

F: much simpler

Question 3

T/F: Viruses cannot reproduce or carry out metabolism outside of a host cell

Answer 3

T: They are dependent on the host cell

Question 4

T/F: Viruses are cells

Answer 4

F: Viruses are not cells; they are very small infectious particles

Question 5

What do viruses consist of?

Answer 5

Nucleic acid enclosed in a protein coat, and some cases, a membranous envelope

Question 6

Viral genomes consist of which 2 things?

Answer 6

Double/single stranded DNA or double/single stranded RNA

Question 7

Viruses are classified as which two kinds of viruses?

Answer 7

DNA or RNA

Question 8

A genome can be what two kinds of shapes of single molecule of nucleic acid?

Answer 8

Linear or circular

Question 9

How many genes do viruses have in their genome?

Answer 9

Between 3 and 2,000

Question 10

The protein shell that encloses the viral genome

Answer 10

Capsid

Question 11

Capsids are built from protein subunits called _______

Answer 11

Capsomeres

Question 12

What are the two types of main structures of viruses that are associated with capsid?

Answer 12

Helical or icosahedral

Question 13

Accessory structures that help viruses infect hosts

Answer 13

Protein spikes

Question 14

Derived from membranes of host cells and surround the capsids of influenza viruses and many other viruses found in animals

Answer 14

Viral envelopes

Question 15

Contain a combination of viral and host cell molecules

Answer 15

Viral envelopes

Question 16

Viruses that infect bacteria; AKA “Phages”

Answer 16

Bacteriophages

Question 17

Have elongated capsid head that encloses their DNA

Answer 17

Bacteriophages

Question 18

T/F: Viruses replicate only in host cells

Answer 18

T: viruses are obligate I trace lunar parasites; can replicate only within a host cell

Question 19

A limited number of host species that can infect

Answer 19

Host range

Question 20

How does a viruses replicate?

Answer 20

Utilizes the cell’s machinery to reproduce

Question 21

What are the best understood of all viruses?

Answer 21

Phages

Question 22

What are phage’s two alternative reproductive mechanisms?

Answer 22

Lytic and lysogenic cycle

Question 23

A phage replicative cycle that culminates in the death of the host cell

Answer 23

Lytic cycle

Question 24

Produces new phages and lyses (breaks open) the host’s cell wall, releasing the progeny virus

Answer 24

Lytic cycle

Question 25

Phage that reproduces only by the Lytic cycle is

Answer 25

Virulent phage

Question 26

Replicates the phage genome without destroying the host

Answer 26

Lysogenic cycle

Question 27

Viral DNA molecule is incorporated into the host cells chromosome

Answer 27

Lysogenic cycle

Question 28

Phage that use both the Lytic and lysogenic cycle are called

Answer 28

Temperate phages

Question 29

The temperate phage that is widely used in biological research

Answer 29

Lambda

Question 30

Integrated viral DNA

Answer 30

Prophage

Question 31

What can trigger the virus genome to exit the bacterial chromosome and switch to the Lytic mode?

Answer 31

Environmental signal

Question 32

Have their own defenses against phages

Answer 32

Bacteria

Question 33

Foreign DNA can be identified as such and cut up by cellular enzymes called

Answer 33

Restriction enzymes

Question 34

Both bacteria and archaea can protect themselves from viral infection with what system?

Answer 34

CRISPR-Cas

Question 35

What does CRISPRs stand for?

Answer 35

Clustered regularly interspaced short palindromic repeats

Question 36

What are the 2 key variables used to classify viruses that infect animals?

Answer 36

an RNA or DNA genome, either single-stranded or double-stranded; presence or absence of a membranous envelope

Question 37

Use reverse transcriptase to copy their RNA genome into DNA

Answer 37

Retroviruses

Question 38

What is the retrovirus that causes AIDS?

Answer 38

HIV (Human Immunodeficiency virus)

Question 39

Viral DNA that is integrated into the host genomes

Answer 39

Provirus

Question 40

Unlike a prophage, remains a permanent resident of the host cell

Answer 40

Provirus

Question 41

What transcribes the pro viral DNA into RNA molecules?

Answer 41

RNA polymerase

Question 42

Name 3 mobile genetic elements

Answer 42

Plasmids, transposons, and viruses

Question 43

Smaller, less complex entities that cause disease in animals

Answer 43

Prions

Question 44

A harmless derivative of a pathogen that stimulates the immune system to mount defense against the harmful pathogen

Answer 44

Vaccine

Question 45

T/F: viral infections cannot be treated by antibiotics

Answer 45

T

Question 46

Widespread outbreak

Answer 46

Epidemic

Question 47

Plant viruses spread disease by 2 major routes

Answer 47

Horizontal and vertical transmission

Question 48

Entering through damaged cell walls

Answer 48

Horizontal transmission

Question 49

Inheriting the virus from a parent

Answer 49

Vertical transmission

Question 50

Infectious proteins that appear to cause degenerative brain disease in animals

Answer 50

Prions

Question 51

Scrapie in sheep

Answer 51

Prions

Question 52

Mad cow disease

Answer 52

Prions

Question 53

Creutzfeldt-Jakob disease

Answer 53

Prions

Question 54

Incorrectly folded proteins, can be transmitted in food, act slowly, and are virtually indestructible

Answer 54

Prions

Question 55

Able to convert a normal form of a protein into the misfiled version

Answer 55

Prion

Question 56

Alzheimer’s and Parkinson’s

Answer 56

Prions