Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microbial world > Lecture 13 and 14 > Flashcards

Lecture 13 and 14 Flashcards

1
Q

What was the first virus to be discovered?

A

Tobacco mosaic virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does tobacco mosaic virus do?

A

Causes tobacco leaves to be mottled, stunts growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Who was the first person to investigate TM disease?

A

Adolf Mayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What did Adolf Mayer find could transfer the disease?

A

Diseases could be transferred in sap between plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What could Adolf Mayer not find?

A

Anything microscopic in the sap causing the disease (something submicroscopic was causing the disease)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Who filtered the sap?

A

Dmitri Ivanovsky

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What did Dmitri Ivanovsky find when he filtered the sap?

A

It could still transfer the disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What did the fact that filtered sap could transfer disease suggest?

A

It was sub-microscopic or a toxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Who discovered that the disease could replicate and therefore was not a toxin:?

A

Martinus Beijerinck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How did Martinus Beijerinck conclude the virus can replicate?

A

Filtered sap causes mottled leaf appearance in a third plant- therefore toxin was not responsible for transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Who tried to culture bacteria from the infected tobacco plant?

A

Martinus Beijerinck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What did the fact that Beijerinck’s cultures didn’t grow suggest?

A

Disease not caused by cultivable bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How did Beijerinck definitively show that tobacco mosaic disease was not caused by a bacterium?

A

He treated the sap with ethanol to damage the membrane. The sap was still infectious, therefore not bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Who first isolated and crystallised TMV virion?

A

Wendell Stanley

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What did Stanley’s crystallized virus remain?

A

Infectious

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What did the fact that TMV remained infectious demonstrate?

A

Viruses have no independent metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Who first viewed TMV virion? How?

A

Kausche, Pfankuch and Ruska

Electron microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the average virus size?

A

20nm diameter to 1000nm length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the cultivable nature of viruses?

A

Obligate intracellular parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What bacteria share small size and cultivatable nature of viruses?

A

Rickettsia/ Chlamydia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the cell structure of viruses?

A

No cellular structure (acellular)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the protein coat around a viruses genome called?

A

Capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What genome do viruses have?

A

A single type of nucleic acid (RNA or DNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a envelope?

A

A lipid layer surrounding the capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What does synthesis result in?
Specialised structures that transfer viral genome to other host cells
26
Generally, where do enveloped viruses come from?
Animal cells with no cell wall
27
Why can't most drugs interfere with viral multiplication?
Would affect host cell function, host enzymes are used to generate the parasites
28
What name is given to viruses that infect fungi?
Mycoviruses
29
What host range do most viruses have?
Limited to usually one host species, specific cell types
30
What virus causes glandular fever?
Epstein-Barr virus
31
What phages infect Escherichia coli?
T-even phages (T2, T4)
32
What cells does influenza A virus infect?
Nose/throat/lungs epithelial cells
33
What cells does Epstein-Barr virus infect?
B-lymphocytes
34
Why is virus host range limited?
Virus requirements: specific receptor/ligand for cell invasion Need certain host factors for viral replication
35
Name a virus that can jump species and expand their host range.
Influenza A virus (has several variants (serotypes))
36
What type influenza A serotype infects birds?
H7N7
37
What serotype of influenza A infects pigs?
H1N1, but can act as a reservoir for all serotypes
38
What serotype of influenza A virus infects humans?
H3N3
39
Why are emerging diseases a big problem?
No natural defenses: we haven't adapted to these diseases
40
What are the 2 life cycle stages for viruses?
Replicating stage, birion
41
What is the replicating stage?
Genome replicating | Active, intracellular disease causing stage
42
What is the virion stage?
Dormant, transmissible stage, survives outside host
43
What is the core of a virion?
Nucleic acid (DNA or RNA)
44
What is the capsid composed of?
Subunits called capsomeres
45
What makes up the capsomeres?
Some viruses, made of one protein | Other viruses, capsomere made of several proteins
46
How does the capsid get put together?
It is self assembling
47
What gives the virus a shape?
The capsid
48
What shape can viruses be?
Helical, complex, polyhedral
49
How are capsomeres arranged in helical viruses?
Arranged in a spiral (coil like)
50
What shape do capsomeres form in polyhedral viruses?
Equilateral triangle, which arrange into polyhedral
51
Most polyhedral viruses are ______ shaped.
Icosahedral (20)
52
What is the enveloped derived from?
Host membrane
53
What can the envelope contain?
Glycoproteins (spikes) encoded by viral and host genome
54
What do spikes on the envelope do?
Function as antigens: involved in host cell invasion and identification
55
What is the other function of the envelope?
Protect virion from enzymes/chemicals
56
Name two enveloped viruses
Influenza | HIV
57
What viruses carry appendages?
Complex viruses (particularly bacteriophages)
58
What do appendages do?
Used to attach virus to host cell
59
Name a non-enveloped polyhedral virus.
Poliovirus
60
Name an enveloped polyhedral virus
Herpes simplex virus
61
Name a non-enveloped helical virus
TMV
62
What shape are viral genomes?
Circular or linear (nucleic acid type irrelevant)
63
Viral genomes can be _____ or __-______
Segmented | Non segmented
64
What is a segmented viral genome?
Several nucleic acid molecules, such as some RNA viruses
65
What are non-segmented viral genomes?
Single nucleic acid molecule (most DNA viruses, some RNA viruses)
66
Single stranded (ss)RNA viruses can be:
+sense or -sense
67
What is +ssRNA?
Can be translated directly by host cell
68
What is -ssRNA?
Converted to +sense before translation
69
How is the + strand made from the - strand?
RNA polymerase synthesises it
70
What must -ssRNA also encode?
RNA polymerase
71
What are two classification systems used to classify viruses?
International committee of taxonomy of viruses | Baltimore classification
72
What does ICTV use?
Nucleic acid type, site of replication, morphology and pathology
73
What is the taxonomic structure of viruses?
Order Family Genus Species
74
What does baltimore classification do?
Take into account unassigned viruses of ICTV | Based on how viruses generate mRNA
75
What 7 groups are baltimore classified viruses split into?
dsDNA, ssDNA, dsRNA, +ssRNA, -ssRNA, +ssRNA-RT, dsDNA-RT
76
Give an example of a virus that undergoes the lytic cycle.
T-even bacteriphage
77
What are the 5 stages of the lytic cycle?
``` Attachment Penetration Biosynthesis Maturation Release ```
78
What enzyme degrades the cell wall of the host when the baseplate of the virus makes contact with the cell wall?
Lysozyme
79
Gene expression is ______, it is not expressed at the same time
Temporal
80
What are the early genes?
Viral genome replication
81
What happens to host DNA?
Viral-induced degredation
82
How does host protein biosynthesis stop?
Viral proteins interfere/repress host translation
83
How long does the lytic cycle take?
About 30 minutes
84
What enzyme breaks down bacterial cell wall during release?
Lysozyme
85
Name a lysogenic phage.
E.coli bacteriophage lambda
86
What are the 7 stages of lysogenic cycle?
``` Attachment Penetration Integration/dormancy Excision Biosynthesis Maturation Release ```
87
What is the first stage of integration?
The viral genome circularises
88
What is the inserted viral DNA called?
Prophage
89
Why are there differences between bacteriphages and animal viruses?
Envelope/non-envelope | Genome structure
90
What are the 6 stages of animal virus replication?
``` Attachment Entry Uncoating Biosynthesis Maturation Release ```
91
Uncoating in animal viruses means that...
can get dormancy phase for some animal viruses (latent disease)
92
What are virion ligands in animal viruses?
Spikes (enveloped) | Fibres (non-enveloped)
93
What happens during attachment of enveloped viruses?
Specific receptor/ligand interaction
94
What happens during fusion entry of enveloped viruses?
Fusion: host cell membrane/viral envelope fuse, capsid released into cytoplasm
95
What happens during endocytosis/pinocytosis entry of enveloped viruses?
Attachment can trigger endocytosis or 'feeding' mechanism pinocytosis
96
What happens during uncoating?
Enzyme mediated degredation of capsid to release viral genome
97
What may the uncoating enzyme be of?
``` Viral origin (poxviruses) Host origin ```
98
How do non-enveloped viruses fuse?
Host cell membrane/viral capsid fuse, viral genome released into host cytoplasm
99
Where do RNA viruses multiply in animals?
The cytoplasm
100
What ways are animal viruses release?
Budding (enveloped), rupturing (non-enveloped viruses)
101
How does budding work?
Capsid associates with and adheres to portion of the host plasma membrane to virus to form a bud
102
What stages do antivirals attack?
Uncoating, viral biosynthesis (nucleic acid replication and protein processing) Release

Microbial world (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions