Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

From Flashcardlet > Micro Viruses > Flashcards

Micro Viruses Flashcards

1
Q

What does it mean to say that viruses are obligate intracellular parasites?

A
  1. They can’t replicate independently without a living host
  2. They are very small in size, much smaller than host
  3. They depend on the host cell’s structures and metabolism for survival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why does a virus depend on the host cell’s structures?

A

It doesn’t have ATP producing mechanisms, ribosomes, enzymes, or cellular material, and therefore it doesn’t have the ability to reproduce

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

What happens to a host cell’s resources when a virus infects the host?

A

The resources are used solely for replication of the virus and no longer propagate the cell

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

How many viruses are there on Earth? Prokaryotes?

A

10^32 viruses, 10^30 prokaryotes

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

Are viruses considered cells? Are they considered life?

A

They are not cells, but they can be considered life because they have hereditary material that is transferred to offspring and they can evolve

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

What is a viron?

A

A fully developed virus particle, considered infectious

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

What are the parts of a virus’s structure?

A
  1. Genome
  2. Capsid
  3. Envelope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the genome?

A

The hereditary material

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

Is a viral genome DNA or RNA?

A

Could be either

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

What is a capsid?

A

The protective protein coating that protects the genome from things like radiation or chemicals

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

What is the envelope?

A

A lipid layer that surrounds the virus

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

What are the two types of cells regarding their envelope structure?

A
  1. Enveloped virus and a naked virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is one unit of a capsid called?

A

Capsomere or a protomer

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

What are some examples of a capsid shape?

A

Filamentous, icosahedral, complex

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

What does a complete virus look like?

A

An icosahedral head with a sheath, pin, baseplate, and tail fibers

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

What structures may be protruding from the envelope surface?

A

Spikes (embedded proteins)

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

What happens to the envelope during infection?

A

It fuses with the host cell membrane

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

How do the spikes of an envelope affect compatibility?

A

The spikes can only bind to certain cell surface receptors and therefore only certain types of cells

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

What happens to the envelope as the virus enters and exits the cell?

A

The envelope fuses with the rest of the cell membrane to make a continuous membrane upon entrance. Upon exiting the virus regains parts of its original envelope along with the host cell membrane (the host cell membrane also acquires spikes because the viral genome encodes for them)

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

What structure does a host probably lack if the virus has an envelope? What types of viruses are typically enveloped?

A

A cell wall; animal viruses

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

How many copies does a virus typically produce while residing in the host cell?

A

About 100 copies

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

What are the three different characteristics a viral genome could have?

A
  1. RNA or DNA
  2. Single or double stranded
  3. Linear or circular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the genome encode for in general?

A

Proteins that the virus cannot acquire from the host cell, like capsid proteins, envelope proteins, and any polymerase it cannot find in the host

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

What is the main characteristic of the viral genome?

A

It is efficient - it has no redundancy in the types of genes that the host cell has (for example, it doesn’t encode for ribosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the two names for the envelope spikes?

A

H and N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What types of viruses have H and N spikes?

A

Influenza virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which viruses mutate more frequently, RNA or DNA?

A

RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are two examples of RNA viruses?

A

Influenza, HIV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why does an RNA virus mutate more frequently?

A

DNA genomes have polymerase that proofread the strand to look for mistakes, RNA does not have the ability to correct mistakes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Is the lack of proofreading abilities good or bad for the virus?

A

It could be both, it could be bad if the new code doesn’t work well, or it could be good if the mistake causes a new attachment protein to be made and now the virus can infect more hosts than before

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How does a virus usually transfer between species?

A

Usually animal to human in beginning stages, but if it develops the mutation it could start to transfer human to human

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the host range?

A

The number of species a virus can infect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is a narrow range?

A

The virus can only infect specific types of host cells, and may only be able to infect one type of cell within a particular host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is an example of a narrow range virus and why?

A

HIV because it can only infect humans and can only infect certain types of human cells.
HPV can only infect human skin cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is a broad range?

A

AKA generalists can infect multiple hosts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is an example of a broad range virus and why?

A

Influenza can infect humans, swine, and birds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is a host range mainly concerning?

A

Attachment and receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What cells does HIV infect?

A

Human cells with CD4 receptors, like T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Which is the virus and which is the disease, HIV/AIDS?

A

HIV is the virus and AIDS is the disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is a disease?

A

A change in the state of health

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Can you be infected with HIV but not have AIDS?

A

Yes, if a person stays on their drug treatment therapy early and long enough they may never exhibit symptoms of AIDS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are some examples of how broad ranges have a limit?

A

Plant viruses can’t infect animals, prokaryotic viruses can’t infect eukaryotes

43
Q

What is the term for viral families?

A

Viridae

44
Q

What are viral classifications into families based on?

A
  1. Type of nucleic acid
  2. Enveloped or non enveloped
  3. Host range
  4. Size and shape
  5. Disease caused
45
Q

What is a viral species?

A

A group of viruses with similar genetic information and host range (given common names)

46
Q

What are the definite steps of viral replication?

A
  1. Attach to a host cell
  2. Entrance of viral genome into host
  3. Synthesis - viral genome copied and viral proteins synthesized
  4. Assembly
  5. Release of progeny viruses from the host
47
Q

What happens to the host cell once the viral copies are released?

A

Usually the cell lyses and dies; if it doesn’t die it remains a infected and continues as a virus factory

48
Q

What does an enveloped virus enter the host cell with (what structures)?

A

Just the capsid and genome

49
Q

What happens to the capsid of the original virus?

A

It is lost during the cell cycle

50
Q

How do the copies of the genome get capsids?

A

The genome is copied 100 times and the capsid proteins are synthesized, then all the parts are assembled into 100 viruses

51
Q

What is a bacteriophage?

A

A virus that can infect bacteria

52
Q

Why are bacteriophages the best studied viruses?

A

Because you can grow their host cells easily and it is not unethical to kill the host cells by infecting them

53
Q

Are phages enveloped or non enveloped?

A

Always non enveloped

54
Q

Do phages have RNA or DNA genomes?

A

DNA

55
Q

What is a lytic phage?

A

The outcome of infection is always host cell death

56
Q

What is another term for lytic phage?

A

Virulent phage

57
Q

What is an example of a lytic phage?

A

T even phages

58
Q

What is a lysogenic phage?

A

Once infected, the host is either killed or the virus becomes dormant

59
Q

What is another term for a lysogenic phage?

A

Temperate phage

60
Q

What is an example of a lysogenic phage?

A

Lambda phage

61
Q

What determines whether the lysogenic phage goes lytic or stays dormant?

A

Something changes in the environment and the phage wakes up and reproduces

62
Q

What organism do both T even and lambda phages infect?

A

E. coli

63
Q

What shape is a T4 phage?

A

Complex

64
Q

What is specific about the tail fibers on a complex shaped virus?

A

Their ends have specific proteins that are compatible to the host surface receptors

65
Q

Why doesn’t a bacteria just evolve so that the phages cannot bind to its surface receptors?

A

The tail fibers attach to the amino acids on the surface of the host on the outside of porins. If these porins changed shape so the tail fibers couldn’t attach, the cell couldn’t bring in necessary resources (maltose, iron) through the porins either

66
Q

What does a phage release in order to enter the cell?

A

It secretes lysozyme, which breaks down the B(1,4) bonds in the peptidoglycan in the cell wall

67
Q

What does the virus do structurally in order to enter the host cell?

A

It contracts its tail sheath and the collar punctures the cell, therefore injecting the DNA genome into the cytoplasm

68
Q

What are the classifications for the genes that are transcribed and translated once the genome enters the host, in order?

A

Early, middle, late - they are turned on in different parts of the life cycle

69
Q

What is an example of an early gene?

A

DNase, which is an enzyme that degrades the host cell DNA but not the viral genome

70
Q

Why does the virus degrade the host cell DNA?

A

So that all the host’s resources go to helping the virus replicate

71
Q

How is the replication of a virus different from binary fission?

A

The virus doesn’t grow to twice its size and then split in half

72
Q

How do the viral copies exit the cell?

A

They release lysozyme that degrades the cell membrane all over, and the cell lyses

73
Q

How are lambda and T even phages structures similar?

A

They look the same except the lambda doesn’t have tail fibers

74
Q

What is different about the replication process for lysogenic phages?

A
  1. Attachment
  2. Entry
  3. Prophage in chromosome*
  4. Replication of chromosome and cell division*
  5. Induction*
  6. Synthesis
  7. Assembly
  8. Release
75
Q

What is the prophage step?

A

The viral genome becomes part of the host cell’s DNA - it is not yet reproducing!

76
Q

What happens when the host cell chromosome replicates and the host cell divides?

A

The viral DNA is copied along with the host cell’s DNA, and copies are made and distributed to both daughter cells containing the viral genome

77
Q

Why is the lysogenic phase good for the virus in the long term?

A

It can wait and wait until the cells copy and reproduce millions of times, therefore creating millions of copies. Then once the virus goes through induction, it makes 100 copies in each of those cells!

78
Q

What is induction?

A

When the virus wakes up due to a change in the environment

79
Q

What happens to the genes of the virus when it switches from lysogenic to lytic?

A

Lytic genes are expressed, no more lambda

80
Q

What is a lambda repressor protein?

A

It attaches to the lytic genes to prevent their expression, and early DNase enzymes are not made.

81
Q

What must happen for a virus to go through induction?

A

The lambda repressor protein must be removed from the lytic gene

82
Q

What results when a phage’s DNA integrates into the host cell chromosome (what are the virus and host now called)?

A

The virus becomes a prophage, and the bacterial cell becomes a lysogen

83
Q

What is the key enzyme in creating a prophage?

A

Integrase

84
Q

What is lysogenic conversion?

A

The bacteria is infected by a lysogenic virus and has an altered phenotype due to the prophage genes

85
Q

What might a bacterial strain produced when infected with a virus?

A

Toxin

86
Q

Why does the bacterial make a toxin only when infected with a virus?

A

Because the viral prophage DNA encodes for it, not the chromosomal DNA

87
Q

What is a common example of a clinical toxin?

A

Botox - botulism toxin

88
Q

What are three examples of bacterial infections that are caused by a toxin?

A
  1. Diphtheria
  2. Cholera
  3. Botulism
89
Q

What triggers a prophage to enter the lytic cycle?

A

Induction occurs when there is a decrease in lambda repressor levels due to an environmental trigger that usually causes DNA damage (radiation, desiccation, chemicals)

90
Q

What does the host cell do when there is DNA damage occurring?

A

Releases the repair protein RecA

91
Q

What does RecA do for the virus?

A

It cleaves the lambda repressor also

92
Q

What are the three stages of culturing lytic viruses?

A
  1. Free virus concentration drops
  2. Eclipse period
  3. Rapid rise period
93
Q

What happens when the free virus concentration drops?

A

The viruses are entering cells and the concentration in the solution drops

94
Q

What is happening during the eclipse period?

A

Synthesis and assembly

95
Q

What happens during the rapid rise period?

A

The host cell lyses and there is a burst of viruses

96
Q

What is provided as food when culturing viruses?

A

Host cells are their food

97
Q

What does the growth of host cells look like on a cultured plate?

A

A confluent lawn

98
Q

What do viruses form on the plate?

A

Plaques where host cells are killed

99
Q

What is a plaque?

A

A colony of viruses

100
Q

What are three forms of where viruses could be grown?

A
  1. Tissue cultures
  2. Embryonated eggs
  3. Animals
101
Q

How much bacteria are killed every day?

A

1/2 the earth’s bacteria are killed every day by viruses

102
Q

How do viruses increase the host cell’s diversity?

A

There is a strong selection for virus-resistant strains

103
Q

What are three examples of where people where susceptible because they were being exposed to a new virus?

A
  1. West Nile virus
  2. Smallpox in the New World
  3. H7N9

From Flashcardlet (133 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions