Chapter 19: Viruses Flashcards

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1
Q

An infectious particle consisting of genes packaged in a protein coat

A

Virus

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2
Q

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

A

F: much simpler

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3
Q

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

A

T: They are dependent on the host cell

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4
Q

T/F: Viruses are cells

A

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

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5
Q

What do viruses consist of?

A

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

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6
Q

Viral genomes consist of which 2 things?

A

Double/single stranded DNA or double/single stranded RNA

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7
Q

Viruses are classified as which two kinds of viruses?

A

DNA or RNA

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8
Q

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

A

Linear or circular

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9
Q

How many genes do viruses have in their genome?

A

Between 3 and 2,000

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10
Q

The protein shell that encloses the viral genome

A

Capsid

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11
Q

Capsids are built from protein subunits called _______

A

Capsomeres

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12
Q

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

A

Helical or icosahedral

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13
Q

Accessory structures that help viruses infect hosts

A

Protein spikes

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14
Q

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

A

Viral envelopes

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15
Q

Contain a combination of viral and host cell molecules

A

Viral envelopes

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16
Q

Viruses that infect bacteria; AKA “Phages”

A

Bacteriophages

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17
Q

Have elongated capsid head that encloses their DNA

A

Bacteriophages

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18
Q

T/F: Viruses replicate only in host cells

A

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

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19
Q

A limited number of host species that can infect

A

Host range

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20
Q

How does a viruses replicate?

A

Utilizes the cell’s machinery to reproduce

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21
Q

What are the best understood of all viruses?

A

Phages

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22
Q

What are phage’s two alternative reproductive mechanisms?

A

Lytic and lysogenic cycle

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23
Q

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

A

Lytic cycle

24
Q

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

A

Lytic cycle

25
Q

Phage that reproduces only by the Lytic cycle is

A

Virulent phage

26
Q

Replicates the phage genome without destroying the host

A

Lysogenic cycle

27
Q

Viral DNA molecule is incorporated into the host cells chromosome

A

Lysogenic cycle

28
Q

Phage that use both the Lytic and lysogenic cycle are called

A

Temperate phages

29
Q

The temperate phage that is widely used in biological research

A

Lambda

30
Q

Integrated viral DNA

A

Prophage

31
Q

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

A

Environmental signal

32
Q

Have their own defenses against phages

A

Bacteria

33
Q

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

A

Restriction enzymes

34
Q

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

A

CRISPR-Cas

35
Q

What does CRISPRs stand for?

A

Clustered regularly interspaced short palindromic repeats

36
Q

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

A

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

37
Q

Use reverse transcriptase to copy their RNA genome into DNA

A

Retroviruses

38
Q

What is the retrovirus that causes AIDS?

A

HIV (Human Immunodeficiency virus)

39
Q

Viral DNA that is integrated into the host genomes

A

Provirus

40
Q

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

A

Provirus

41
Q

What transcribes the pro viral DNA into RNA molecules?

A

RNA polymerase

42
Q

Name 3 mobile genetic elements

A

Plasmids, transposons, and viruses

43
Q

Smaller, less complex entities that cause disease in animals

A

Prions

44
Q

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

A

Vaccine

45
Q

T/F: viral infections cannot be treated by antibiotics

A

T

46
Q

Widespread outbreak

A

Epidemic

47
Q

Plant viruses spread disease by 2 major routes

A

Horizontal and vertical transmission

48
Q

Entering through damaged cell walls

A

Horizontal transmission

49
Q

Inheriting the virus from a parent

A

Vertical transmission

50
Q

Infectious proteins that appear to cause degenerative brain disease in animals

A

Prions

51
Q

Scrapie in sheep

A

Prions

52
Q

Mad cow disease

A

Prions

53
Q

Creutzfeldt-Jakob disease

A

Prions

54
Q

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

A

Prions

55
Q

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

A

Prion

56
Q

Alzheimer’s and Parkinson’s

A

Prions