Brainscape's Knowledge GenomeTM

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


See full index

MIMM 324 > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What information is encoded in a viral genome?

A

Replication of viral genome
Assembly and packaging of the genome
Regulation and timing of the replication cycle
Modulation of host défenses
Spread to other cells

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

All viral genomes must make ____ that can be read by host ribosomes.

A

mRNA

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

Is mRNA + or - polarity

A

+

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

What is the + strand?

A

DNA or RNA that is the coding strand (starts with AUG)

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

What is the - strand?

A

DNA or RNA that is the template strand. Does not contain open reading frame

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

True or false: All +RNAs are mRNAs

A

False. Ex: Genomic RNA vs sub-genomic mRNAs

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

What are the seven Baltimore classes?

A
  1. ds DNA
    • ssDNA
  3. ds RNA
    • ssRNA
    • ssRNA
    • ss RNA reverse transcriptase
  7. ds DNA reverse transcriptase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe Baltimore Class I viruses

A

Transcribe dsDNA to +mRNA

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

What are two Baltimore class I viruses whose genomes are copied by host DNA polymerases?

A

Polyomaviridae, Papillomaviridae

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

What are two Baltimore Class I viruses that encode their own DNA polymerase?

A

Adenoviridae
Poxviridae (replicates in cytoplasm, therefore needs to create its own DNA pol)

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

Describe Baltimore Class II viruses

A

Convert - or + ssDNA to dsDNA and then transcribes to mRNA

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

True or false: Baltimore class II viruses can be circular or linear

A

True

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

Which Baltimore class viruses use an RdRp?

A

dsRNA, + RNA and - RNA

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

What is RdRp?

A

RNA-dependent RNA polymerase
To make mRNAs and RNA genomes from RNA templates

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

Which Baltimore class viruses use reverse transcriptase

A

ssRNA-RT and dsDNA-RT

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

Describe Baltimore Class III viruses

A

dsRNA converted to mRNA by RdRp

17
Q

Describe Baltimore Class IV viruses

A

mRNA can be directly translated

18
Q

Describe Baltimore Class V viruses

A

-RNA gets converted to +RNA through RdRP
Can be segmented or non-segmented

19
Q

Describe Baltimore Class VI viruses

A

+RNA gets converted - ssDNA by reverse transcriptase and then to dsDNA

20
Q

Describe Baltimore Class VII viruses

A

Gapped dsDNA converted to full dsDNA and then transcribed to mRNA

Uses reverse transcriptase when turning +RNA to dsDNA (replicating genome)

21
Q

What is reassortment?

A

Multiple viruses co-infect the same cell
Leads to rapid evolution

22
Q

How were viral stocks maintained in the 1900s?

A

Continual passage from animal to animal

23
Q

Before cell culture, how were viruses propagated?

A

In embryonated chicken eggs
5-14 days after fertilization, hole drilled in shell, the location of viral injection depends on site appropriate for its replication

24
Q

What are the two types of cell cultures?

A

Primary cell cultures
- prepared from animal tissues
- limited life span

Continuous cell lines
- single cell type that can be propagated indefinitely in culture
- HeLa cells: cancer cells
- Tumor tissue or immortalized primary cells
- May not resemble the cell of origin

25
Q

What is evidence of viral growth in culture cells?

A

Rounding up of cells, detachment, cell lysis, syncytial formation (cell fusion), nuclear shrinking/swelling, accumulation of virions/viral proteins, membrane alteration

26
Q

What is the virus titer?

A

Concentration of a virus in a sample

27
Q

What is the plaque assay?

A

Quantitative measure of infectious virus
Count # of infectious viral particles in a suspension

28
Q

How do you calculate the titer in a plaque assay?

A

PFU/volume plated x dilution factor

29
Q

What is a focus-forming unit assay?

A

Modification of the plaque assay for viruses that do not lyse cells

After viral infection, cells are permeabilized and stained with an antibody against a viral protein

30
Q

What is the particle-to-PFU ratio?

A

of physical particles divided by the # of infectious particles

31
Q

Why are viral particles not always successful at infection?

A

Damaged particles, mutations, empty particles, complexity of viral life cycles, antiviral defenses

32
Q

What is MOI

A

Multiplicity of infection
Average number of cells added per cell (not the same as the # of infectious particles each cell receives)

Depends on random collision of virions and cells

33
Q

How do you calculate the fraction of cells infected by one or more viral particles?

A

P(k) = (e^-m) (m^k)/k!
P(k) = fraction of cells infected by k virus particles
m=MOI
e = Euler’s number (approx 2.72)
k! = factorial of k

Fraction of uninflected cells = P(0) = e^-m
Fraction of cells infected with one particle = P(1) = (e^-m)m
Fraction of cells multiply infected = P(>1) = 1-(e^-m)(1+m)

34
Q

How is MOI used in research?

A

Low MOI: experiment requires multiple cycles of infection
High MIO: when every cell in culture needs to be infected
Optimal MOI: optimize number of cells that will be infected with a single viral particle

MIMM 324 (10 decks)

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