21.1 Annotated

Question 1

tobacco mosaic virus

Question 2

virus

Answer 2

noncellular parasitic entity unclassifiable in kingdoms; infects all organism types, cannot grow, replicate using host; visible under TEM

Question 3

Viral evolution hypothesis

Answer 3

1) progressive: escaped RNA/DNA/transposon/cell w/ reentry capabilities
2) regressive: evolved from free-living cells or intracellular prokaryotic parasites
3) virus first: virus then cells

Question 4

virus molecular systematics

Answer 4

emerging field, compares sequenced genetic material to determine origins of viruses

Question 5

noncellular

Answer 5

no cellular structure, lacks most components: organelles, ribosomes, plasma membrane

Question 6

capsid

Answer 6

outer protein coating virion’s nucleic acid core

Question 7

(viral) envelope

Answer 7

protein and phospholipid membrane derived from host cell

Question 8

bacteriophages

Answer 8

viruses that infect bacteria
ex: T4 bacteriophage

Question 9

capsomeres

Answer 9

capsid proteins encoded in viral genome

Question 10

viral receptors

Answer 10

glycoproteins that attach to host cells receptors

Question 11

matrix proteins

Answer 11

stabilize envelope and assemble progeny virions

Question 12

virus core

Answer 12

contains viral genome

Question 13

RNA viruses

Answer 13

rabies, retroviruses

Question 14

DNA viruses

Answer 14

HSVs, smallpox

Question 15

ss Viruses

Answer 15

rabies, retroviruses

Question 16

ds Viruses

Answer 16

HSVs, smallpox

Question 17

linear viruses

Answer 17

rabies, retros, HSVs, smallpox

Question 18

circular viruses

Answer 18

HPVs, many bacteriophages

Question 19

naked icosahedral

Answer 19

hep A, polioviruses

Question 20

enveloped icosahedral

Answer 20

epstein-barr, HSV, rubella, yellow fever, HIV-1

Question 21

enveloped helical

Answer 21

influenza, mumps, measles, rabies

Question 22

complex (capsid cx)

Answer 22

herpesviruses, smallpox, hep B, t4 bacteriophage

Question 23

Baltimore classification

Answer 23

(david baltimore, 1970s) groups viruses by morphology, genome, and how the mRNA is produced during replicative cycle of virus

Groups I-VII

Question 24

Group I (BCx)

Answer 24

-dsDNA
-mRNA transcribed directly from DNA template
-ex: HSV

Question 25

Group II (BCx)

Answer 25

-ssDNA -DNA converted to dsDNA before RNA is transcribed -parvovirus

Question 26

Group III (BCx)

Answer 26

-dsRNA -mRNA is transcribed from RNA genome -rotavirus

Question 27

Group IV (BCx)

Answer 27

ssRNA (+) genome fnxs as mRNA common cold picornavirus

Question 28

Group V (BCx)

Answer 28

ssRNA (-) mRNA is transcribed from the RNA genome rabies (rhabdovirus)

Question 29

Group VI (BCx)

Answer 29

ssRNA w/ reverse transcriptase 1) reverse transcriptase makes DNA from RNA genome 2) DNA incorporated into host genome 3) mRNA is transcribed from incorporated DNA HIV

Question 30

Group VII (BCx)

Answer 30

dsDNA w/ reverse transcriptase DNA replicated thru RNA intermediate RNA may serve directly as mRNA or as a template to make mRNA Hepatitis B (hepadnavirus)

Question 31

How were viruses first discovered? How were they detected?

Question 32

What are the three hypotheses about viral evolution?

Question 33

What is the general structure of a virus?

Question 34

What are the basic shapes of viruses?

Question 35

What past classification systems were used?

Question 36

What are emerging classification systems (C.S.) for viruses?

Question 37

What is the basis for the Baltimore C.S.