Unit 2.3: Viruses, Prions, and Viroids

Question 1

Viruses infect all living things
Viruses are everywhere
Viruses are catalysts for biogeochemical cycling Humans carry viral genomes

Question 2

VIRUS

a genetic element (not a cell) that can replicate only inside a living cell, called the _____

Answer 2

host cell

Question 3

• Comprise genetic material of (DNA/RNA)
• possess its own genomes
• rely on the host cell for energy, metabolic intermediates, and protein synthesis.
• obligate intracellular parasites

Answer 3

VIRUS

Question 4

an extracellular form of the virus

Answer 4

VIRION

Question 5

A complete infectious virus particle containing the genetic material, capsid and envelope (protein coat)

Answer 5

VIRION

Question 6

deliver its DNA or RNA genome into the host cell

Answer 6

VIRION

Question 7

viruses cannot replicate unless the virus itself has gained entry into a suitable host cell, a process called _____

Answer 7

infection

Question 8

A protein shell of virion containing the virus genome (capsomeres)

Answer 8

CAPSID

Question 9

animal viruses contain an outer layer consisting of protein plus lipid called the _____

Answer 9

envelope

Question 10

The inner structure of nucleic acid plus capsid protein

Answer 10

Nucleocapsid

Question 11

Lipid-containing layers surrounding nucleocapsid derived from the membranes of the host cell.

Answer 11

ENVELOPE

Question 12

extension in the surface and act as attachment projections or as enzymes.

Answer 12

Glycoprotein spikes

Question 13

EXAMPLES OF VIRUS

Answer 13

Ebola virus (50-80 nm, 10,000-14,000 nm in length)

Smallpox virus (200 nm)

Coronavirus (160 nm)

Poliovirus (28 nm)

Question 14

Most viruses are smaller than prokaryotic cells, ranging in size from ______

Answer 14

0.02 to 0.3 μm (20–400nm).

Question 15

Viral structure: Morphology

_____ - Tobacco mosaic virus
_____ - Adenovirus
_____ - Influenza virus
_____ - Bacteriophage

Answer 15

HELICAL
POLYHEDRAL
ICOSAHEDRAL
COMPLEX

Question 16

a spiral shape in which the capsid curves cylindrically around a central axis (nucleic acid core).

Answer 16

Helical

Question 17

these are many- sided viruses (20 triangular sides and 12 vertices, or corners)

Answer 17

Polyhedral

Question 18

shaped like spheres

a geometrical shape with 20 faces each in the shape of an equilateral triangle.

Answer 18

ICOSAHEDRAL

Question 19

_____ are a type of enveloped virus.

Answer 19

Coronaviruses

Question 20

Combination of polyhedral and helical shape

Have a complex outer wall or head-tail morphology

Answer 20

COMPLEX

Question 21

_____ help in anchoring the virus to the bacterial cell wall.

Answer 21

Tail fibers

Question 22

• Naked icosahedral
• Enveloped icosahedral
• Enveloped helical
• naked helical
• complex with many proteins

Answer 22

cashed classification

Question 23

growth curve

Answer 23

Eclipse
Latent Period
Maturation Period

Question 24

GROWTH CURVE
______: infectious virions cannot be detected in the growth medium

_____: viral nucleic acid replicates and protein synthesis occurs.

_____: virus nucleic acid and protein are assembled into mature virions and then released.

Answer 24

Eclipse
Latent Period
Maturation Period

Question 25

VIRAL CLASSIFICATION BY HOSTS THEY INFECT (BVFAAPP)

Answer 25

BACTERIAL viruses (bacteriophages) VIRAL viruses (Virophages) FUNGAL viruses (Mycophages) ARCHAEAL viruses ANIMAL viruses PLANT viruses PROTOZOAN viruses

Question 26

genome: DNA types: _____

Answer 26

ssDNA and dsDNA

Question 27

genome: RNA types: _____

Answer 27

ssRNA and dsRNA

Question 28

Contain circular genome, infects E. coli

Answer 28

φX174

Question 29

Filamentous with helical symmetry, infects E. coli

Answer 29

M13

Question 30

Has an icosahedral head, helical tail and several tail fibers. It generates mutations and infects E. coli

Answer 30

Mu

Question 31

Small DNA that infects E. coli

Answer 31

T7

Question 32

Double-Stranded DNA Bacteriophages:_____ and ______

Answer 32

T7 and Mu

Question 33

Single-Stranded DNA Bacteriophages:_____ and _____

Answer 33

φ X174 and M13

Question 34

DNA ARCHAEAL VIRUSES

Answer 34

SSV VIRUS SIFV ATV

Question 35

Spindle-shaped, often cluster in rosettes. Infects Sulfolobus.

Answer 35

SSV VIRUS

Question 36

Rigid, helical rod-shaped structure. Infects Sulfolobus

Answer 36

SIFV

Question 37

Spindle-shaped with tails (tubes). Infects hyperthermophile Acidianus

Answer 37

ATV

Question 38

Uniquely replicating DNA animal viruses

Answer 38

Pox virus Adenoviruses

Question 39

Brick-shaped, causes disease in humans and animals (Smallpox, cowpox and Vaccinia viruses)

Answer 39

Pox virus

Question 40

Group of small and naked icosahedral viruses causing mild respiratory infections in humans

Answer 40

Adenoviruses

Question 41

Dna tumor viruses

Answer 41

Polyomavirus SV40 Herpesviruses

Question 42

_____ Naked icosahedral virus. Inactivate host cell proteins that control cell division. _____ Enveloped, cause fever blisters, genital herpes, and shingles

Answer 42

Polyomavirus SV40 Herpesviruses

Question 43

Positiv - strand RNA Viruses

Answer 43

Bacteriophage MS2 Poliovirus Coronaviruses

Question 44

______ Icosahedral capsid, Infects cells of E. coli ______ One of the smallest of all virus. Infects cells of E. coli and can infect a person’s spinal cord _____ Appearance having a “crown”, causes respiratory infections

Answer 44

Bacteriophage MS2 Poliovirus Coronaviruses

Question 45

Negative-Strand RNA Animal Viruses

Answer 45

Rabies Virus Influenza Virus

Question 46

_____ Bullet-shaped, causes rabies. _____ Buds as it leaves the cell, virions do not have a uniform shape.

Answer 46

Rabies Virus Influenza Virus

Question 47

Double-stranded RNA virus Consist of nucleocapsid surrounded by a double shell of icosahedral symmetry

Answer 47

Rotavirus

Question 48

Infect animals, plats, fungi, and a few bacteria. Cause of diarrhea in infants

Answer 48

Rotavirus

Question 49

Viruses that Use Reverse Transcriptase

Answer 49

Retroviruses Hepadnaviruses

Question 50

Viruses that Use Reverse Transcriptase _____ Have RNA genomes. Cause of AIDS and some forms of cancer. _____ Have DNA genomes. Causes transient and chronic liver infections.

Answer 50

Retroviruses Hepadnaviruses

Question 51

Infectious agents that resemble viruses (subviral agents) Lack either nucleic acid or protein NOT viruses

Answer 51

PRIONS AND VIROIDS

Question 52

Proteinaceous Infectious Particle

Answer 52

PRIONS

Question 53

In 1982, _____ proposed that there were infectious proteins.

Answer 53

Stanley Prusiner

Question 54

Infectious agents whose extracellular form consists entirely of protein. Proteins that are unique in their ability to reproduce on their own and become infectious.

Answer 54

PRIONS

Question 55

is a host gene that encodes

Answer 55

Prnp (“Prion protein”)

Question 56

This is primarily found in the neurons of healthy animals, especially in the brain

Answer 56

Native form known as PrPc (Prion protein cellular)

Question 57

identical in amino acid sequence to PrPc from the same species, but has a different conformation.

Answer 57

PrPSc (Prion proteins scrapie)

Question 58

TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES

Answer 58

Transmissible: the causative agent is infectious. Spongiform: development of holes in the brain, making it appear like a sponge. Encephalopathy: disease of the brain.

Question 59

PRION DISEASES 1. _____ - Sheep 2. _____ - (BSE or “mad cow disease”) - Cattle 3. _____ - Deer and Elk 4. _____ - Humans

Answer 59

1. Scrapie 2. Bovine Spongiform Encephalopathy 3. Chronic Wasting Disease 4. Kuru and variant Creutzfeldt-Jakob disease

Question 60

Infectious RNA molecules that differ from viruses (lack protein and consist of low molecular weight RNA) Small, circular, single-stranded RNA molecules and naked RNA - no protein capsid

Answer 60

Viroids

Question 61

Cause a number of important plant diseases _____ color change in the foliage, smaller leaves, and spindle-like elongation of the tubers. _____ Leaf spots, reduced leaflets, reduced crown and stunted growth

Answer 61

coconut cadang-cadang viroid potato spindle tuber viroid

Question 62

VIROID STRUCTURE viroid RNA is a single-stranded (covalently closed circle) its extensive secondary structure makes it resemble a _____ double-stranded molecule with closed ends by intra-strand base pairing.

Answer 62

hairpin-shaped

Question 63

VIROID MOVEMENT INSIDE PLANT Does not use receptors to enter the host cell viroid enters a plant cell through the _____ Once, inside, they move from cell to cell via _____ replicate either in a nucleus or the chloroplast

Answer 63

wound plasmodesmata