Brainscape's Knowledge GenomeTM

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


See full index

Microbiology > Lecture 5 > Flashcards

Lecture 5 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Who discovered the tobacco mosaic virus?

A

Ivanovski and Beijerinck

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

What are the roles of viruses?

A

Infect cells and influence their genetic makeup

Shape the way cells, tissues, bacteria, plants, and animals have evolved

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

How did viruses use to be classified?

A

For many years, animal viruses were classified on the basis of their hosts and the diseases they caused

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

How are viruses classified now?

A
  • hosts and diseases they cause
  • structure
  • chemical composition
  • similarities in genetic makeup
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Do viruses resemble cells?

A

Viruses bear no resemblance to cells and lack any of the protein-synthesizing machinery found in cells

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

What is the viral structure?

A
  • Viral structure is composed of regular, repeating subunits that give rise to their crystalline appearance
  • Contain only those parts needed to invade and control a host cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the component capsid of virus?

A

protein shell that surrounds the nucleic acid

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

What is the component envelope of a virus?

A

external covering of a nucleocapsid, usually a modified piece of the host’s cell membrane

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

What is the component spikes of a virus?

A
  • can be found on naked or enveloped viruses
  • project from the nucleocapsid or the envelope
  • allow viruses to bind to host cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the component virion of a virus?

A

a fully formed virus particle capable of establishing an infection in a host cell

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

What are the 3 types of capsids?

A

Helical (can be enveloped), Icosahedral (can be enveloped), and Complex (can’t be enveloped)

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

What are enveloped viruses?

A

take a bit of the cell membrane when they are released from a host cell

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

What do enveloped viruses bud from?

A

cell membrane
nuclear envelope
endoplasmic reticulum

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

What are the facts about the viral envelope?

A
  • Viral envelope differs significantly from the host’s membranes
  • some or all of the regular membrane proteins are replaced with viral proteins
  • some envelope proteins attach to capsid proteins
  • glycoproteins are exposed on the outside of the envelope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Do viruses contain DNA or RNA?

A

One or the other, but not both

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

What are bacteriophages?

A

most contain double-stranded DNA, but some RNA types exist as well

every bacterial species is parasitized by various specific bacteriophages

often make the bacteria they infect more pathogenic

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

What are T-even bacteriophages?

A

Infect Escherichia coli
icosahedral capsid head

central tube

collar

base plate

tail pins

fibers

18
Q

What are the 8 steps of the t-even bacteriophage life cycle?

A

1.Absorb to host bacteria using specific receptors on the bacterial surface
2.Nucleic acid penetrates after being injected through a rigid tube inserted through the cell wall and membrane
nucleic acid entry causes cessation of host cell DNA replication
3.No uncoating is necessary (will talk about in animal viruses)
4. Host machinery used for viral replication and synthesis of viral proteins
5.Parts spontaneously assemble into bacteriophages
6. An average-size Escherichia coli cell can contain up to 200 new phage units
7.Eventually the cell becomes so packed with viruses that it lyses (splits open), releasing mature virions
-process hastened by viral enzymes produced late in the infection cycle that digest the cell envelope, weakening it
8.Upon release, virulent phages can spread to other susceptible bacterial cells and begin a new cycle of infection

19
Q

What is lysogeny?

A

a condition in which the host chromosome carries viral DNA

20
Q

What are tmeperate phages?

A

undergo adsorption and penetration

do not undergo replication or release immediately

21
Q

Is lysogeny the most or least deadly?

A

Least deadly

22
Q

What is induction?

A

virus in a lysogenic cell becomes activated and progresses directly into viral replication

23
Q

What is the danger of lysogeny in human disease?

A

Occasionally phage genes in the bacterial chromosome cause the production of toxins or enzymes that cause pathology in the human

24
Q

What is lysogenic conversion?

A

when a bacterium acquires a new trait from its temperate phage

25
Q

What are the general phases of the animal viral replication cylce?

A
  1. adsorption
  2. penetration
  3. uncoating
  4. synthesis
  5. assembly
  6. release
26
Q

What is the length of viral rreplication?

A

The length of the replication cycle varies from 8 hours in polioviruses to 36 hours in herpesviruses

27
Q

Where is DNA transcribed in eukaryotic cells?

A

DNA in eukaryotic cells is transcribed to RNA in the nucleus by polymerases (transcription)

28
Q

Where does RNA go after being transcribed?

A

The RNA exits the nucleus. The RNA is read by ribosomes in the cytoplasm and becomes proteins that have some function within the cell, or are released from the cell. (translation)

29
Q

What is undercoating?

A

enzymes in the vacuole dissolve the envelope and capsid

virus fuses with the wall of the vesicle

viral nucleic acid is released into the cytoplasm

30
Q

Where does replication and protein production occur in DNA viruses?

A

enter the host cell’s nucleus and are replicated and assembled there

31
Q

Where does replication and protein production occur in RNA viruses?

A

replicated and assembled in the cytoplasm

32
Q

Where does replication and protein production occur in Retroviruses?

A

Retroviruses turn their RNA genomes into DNA in the cytoplasm, then replicate within the nucleus

33
Q

What are retroviruses?

A

two copies of (+) sense RNA that don’t act as mRNA
Reverse transcriptase – turn the viral RNA into ssDNA, which is then replicated to dsDNA
dsDNA moves to nucleus and turns into provirus in host cell chromosome (permanently integrates into host genome)
Can remain for indefinite amount of time, passed to subsequent generations
New viral DNA that was integrated into host chromosome now used to make mRNA, which goes to cytoplasm to be translated and assembled

34
Q

Do RNA viruses go through transcription?

A

No

35
Q

What are cytopathic effects?

A

virus-induced damage to the cell that alters its microscopic appearance

36
Q

What are types of cytophathic effects?

A

gross changes in shape and size
development of intracellular changes
inclusion bodies: compacted masses of viruses or damaged cell organelles in the nucleus and cytoplasm
syncytia: fusion of multiple host cells into single large cells containing multiple nuclei

37
Q

What is a provirus?

A

a persistent infection in which the viral DNA is incorporated into the DNA of the host

may remain hidden in brain cells for many years, causing progressive damage and loss of function

38
Q

what do viruses require as their medium?

A

living cells

39
Q

What are the primary purposes of viral cultivation?

A

isolate and identify viruses in clinical specimens

prepare viruses for vaccines

do detailed research on viral culture, multiplication cycles, genetics, and effects on host cells

40
Q

What are plaques?

A

areas where virus-infected cells have been destroyed and show up as a clear, well-defined patches in the cell sheet

41
Q

What are the characteristics of prions?

A
  • Composed entirely of protein
  • Contain no nucleic acid
  • Questions still remain as to how the agent is propagated, since all other infectious agents require nucleic acid
  • Changes conformation of normal PrP to that of prion PrP
42
Q

What are viroids?

A

Viruslike agents that parasitize plants

About one-tenth the size of an average virus

Composed of naked strands of RNA, lacking a capsid or any other type of coating

Significant pathogens in economically important plants: tomatoes, potatoes, cucumbers, citrus trees, chrysanthemums

Microbiology (12 decks)

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