Brainscape's Knowledge GenomeTM

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


See full index

SLE111 Cells And Genes > Module 17: Viruses > Flashcards

Module 17: Viruses Flashcards

1
Q

What are viruses?

A

Parasitic simple genetic systems that are not cells.

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

Why isn’t viral evolution known?

A

Viruses have not left a fossil record.

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

What is a virion?

A

A single complete viral particle as it exists in its infectious form outside of the cell.

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

What size are most virions?

A

20 to 250 nanometres

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

What emerging field of study aims to explain the origin of viruses?

A

Virus molecular systematics.

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

What is the structure of a virus?

A

A nucleic acid enclosed by a protein coat.
Can also have an outer envelope and/or additional proteins such as enzymes.

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

What are capsomers?

A

The protein subunits of the viral protein coat.

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

What is a capsid?

A

The protein coat of a virus that surrounds its genetic material.

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

What genetic material is characteristic of viruses?

A

Virus can have different forms of genetic material:

  1. DNA or RNA.
  2. Double-stranded or single-stranded.
  3. Linear or circular.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do mutations occur more in RNA viruses?

A

RNA polymerase enzymes are more likely to make copying errors due to lack of proof reading capacity.

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

What are the basics of viral replication?

A
  1. Recognise and attach to specific cell before entering it.
  2. Copy viral genome and manufacture proteins.
  3. Progeny virus must escape the host cell to infect other cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a permissive cell?

A

Also known as a host cell.
A cell that allows a virus to occupy and replicate within it.

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

Why are viruses specific?

A

They require a viral receptor on the host cell surface to attach.

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

Can viruses replicate on their own?

A

No.
Viruses can only replicate within host cells.

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

What are cytopathic effects?

A

The structural changes or damage in cells that are caused by viruses.

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

What is virus budding?

A

Virions leaving the cell individually, rather than all at once through cell lysis.

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

What causes viral symptoms?

A
  1. Cell damage caused by the virus.
  2. The immune response to the virus.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 6 normal steps of viral infection/reproduction?

A
  1. Attachment.
  2. Penetration.
  3. Uncoating.
  4. Replication.
  5. Assembly.
  6. Release.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are 3 ways viruses can enter the host cell?

A
  1. The nucleic acids of viruses leave the capsid outside the cell.e.g. as in bacteriophages
  2. Endocytosis. (Cell membranes surrounds and engulfs entire virus.) e.g., animal and plant viruses
  3. Viral envelope fuses directly with the cell membrane.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an example of viruses with glycoprotein spikes?

A

Adenoviruses

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

What is the name of viruses that infect bacteria?

A

Bacteriophages

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

What are the methods of reproduction for double-stranded DNA viruses?

A
  1. The lytic cycle.
  2. The lysogenic cycle.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the latent form of a bacteriophage integrated into a host cell?

A

A prophage.

24
Q

What does CRISPR stand for?

A

Clustered Regular Interspaced Short Palindromic Repeats

25
Q

What are the steps of the lytic cycle?

A
  1. Attachment.
  2. Entry of phage DNA and degradation of host DNA.
  3. Synthesis of viral genomes and protein.
  4. Self-assembly.
  5. Release.
26
Q

What are the steps of the lysogenic cycle?

A
  1. Attachment.
  2. Integration in bacterial chromosomes, becoming a prophage.
  3. Bacterium reproduces normally, copying the prophage into its daughter cells.
27
Q

Can viruses change reproduction cycling?

A

Yes.
They can change form operating in a lysogenic cycle to a lytic cycle if conditions are correct.

28
Q

What are retroviruses?

A

Single-stranded RNA viruses that infect animal cells and involve using a DNA intermediate to perform reverse transcription.

29
Q

Which enzyme enables RNA to DNA conversion?

A

Transcriptase.

30
Q

What is it called when infection of a cell by a bacteriophage results in the production of new virons?

A

A productive infection

31
Q

How can viruses exist in tissues for long periods of time without producing new virions?

A

Through a process called latency.

32
Q

What are most plant viruses?

A

Single-stranded RNA viruses.

33
Q

What must occur for a plant virus to enter a new host cell?

A

Some form of mechanical damage.

34
Q

The transfer of a virus from one plant to another is known as?

A

Horizontal transmission.

35
Q

The inheritance of a virus from a parent plant is called?

A

Vertical transmission.

36
Q

What is plasmodesma?

A

The microscopic cyctoplasmic canals through adjacent plant cell walls that enable communication and the transportation of molecules.

37
Q

What is hypoplasia?

A

The underdevelopment or incomplete development of a tissue or organ.
Decreased cell growth.

38
Q

What is hyperplasia?

A

also known as hypergenesis
The overgrowth of cells in a healthy tissue or organ.
Abnormal proliferation of cells.

39
Q

What are RNA viruses so deadly?

A
  1. High mutation rates.
  2. Travel leading to high rates of dissemination.
  3. Spread of existing viruses from animals. ‘natural reservoirs’
40
Q

What is antigenic drift?

A

Random mutations occurring in virus genes resulting in genetic variation.e.g. new virus strains

41
Q

What are the envelopes on viruses made of?

A

Host cell membranes.
E.g. a virus may have a phospholipid membrane containing host cell proteins and glycoproteins.

42
Q

What are HeLa cells?

A

Immortal cells used for many important discoveries that were developed from a cervical cancer caused by HPV.

43
Q

How are bacteriophages uses in genetic engineering?

A

Bacteriophages are used as vectors - carriers that transfer DNA from one organism to another.

44
Q

Can viruses cause cancer?

A

Yes.
e.g. HPV encourages uncontrolled cellular growth, resulting in cervical cancer.

45
Q

What are the steps of retrovirus infection?

A
  1. Envelope glycoproteins enable the virus to bind to cells.
  2. Viruses fuse with the cell’s plasma membrane, releasing viral proteins and RNA.
  3. Reverse transcriptase catalyses DNA synthesis complimentary to the viral RNA.
  4. Reverse transcriptase catalyses a second DNA strand complimentary to the first.
  5. The double-stranded DNA is incorporated into the bacterial DNA.
  6. The host cell produces new viruses through DNA to RNA transcription.
46
Q

What allows for the alcohol based elimination of viruses?

A

Viral envelopes.

47
Q

What is the main cause of antigenic drift in RNA viruses?

A

RNA virus genome replication by RNA-dependent RNA polymerase not have a proof reading capacity.
This results in many mutations being introduced, leading to antigenic drift through a slow change in surface antigens.

48
Q

What is dissemination?

A

The property of being diffused or dispersed.
Or, the act of spreading or dispersing.

49
Q

What is the term for irreversible cellular injury and eventually death due to pathological processes?

A

Necrosis.

50
Q

What is an antigen?

A

Any substance capable of stimulating an immune response.

51
Q

What is the primary method of controlling viral disease?

A

Vaccination.

52
Q

Vaccines are prepared using…?

A
  1. Live viruses.
  2. Killed viruses.
  3. Molecular subunits of the virus.
53
Q

What is the main issue with using live viral vaccines?

A

The low but significant danger that the viruses reverts back to its disease-causing form through mutations.

54
Q

Are live viral vaccines more efficient than killed vaccines?

A

Yes. Usually.

55
Q

How are live vaccines usually made?

A

Attenuating wild-type viruses by growing them in different conditions than they are used to in host tissues.
Adapting to different conditions causes mutations in the viral genome, inhibiting its ability to cause disease in host tissue while still activating the immune response.

SLE111 Cells And Genes (17 decks)

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