Brainscape's Knowledge GenomeTM

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


See full index

Block 1 - Fundamental Principles > Microbiology > Flashcards

Microbiology Flashcards

0
Q

What is a virion?

A

Complete infectious particle, assembly of proteins surrounding nucleic acid core

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

What two shapes can a capsid have?

A

Icosahedral or helical

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

What is a virus?

A

An obligate intracellular parasite

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

What is the range in sizes for clinically relevant viruses?

A

From 20-30 nm (picornaviruses) to 300 nm (poxviruses)

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

What are the different genomes a virus can have?

A 
Single stranded DNA
Double stranded linear DNA
Double stranded circular DNA
Single strand positive or negative RNA
Single stranded Segmented RNA
Double stranded segmented RNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is RNA virus replication so error prone?

A

Viral RNA polymerase lacks proof reading function

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

What kind of DNA do most DNA viruses have? What about papovavirus? Parvovirus? Circovirus?

A

Linear dsDNA
Circular dsDNA
ss linear DNA
Circular ssDNA

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

What are classification schemes for animal viruses?

A 
Physical/chemical parameters 
Enveloped vs naked
Morphology
Capsid symmetry
Genomic nucleic acid - especially important
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the current virus classification nomenclature?

A

Family/subfamily/genus/species/strain

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

What is the virus life cycle?

A
  1. Attachment to surface of target cell
  2. Penetration into cell
  3. Uncoating
  4. Replication
  5. Assembly of virion components
  6. Release of infectious progeny virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where do most RNA viruses and most DNA viruses carry out synthetic events and what is an exception to each?

A

RNA - cytoplasm - flu

DNA - nucleus - pox

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

What is virus entry into the host cell dependent on?

A

Prior high affinity interactions between the virus and cell that ultimately trigger internalization

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

What three possible mechanisms are responsible for virus penetration?

A
  1. Translocation of entire virion across pm
  2. Endocytosis of virus resulting in accumulation in cytoplasmic vacuoles
  3. Fusion of cell membrane with virion envelope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does in coating mark the beginning of?

A

Eclipse phase when no infectious visions can be recovered

Not present in bacteria - can always get viable sample

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

How does replication of picornaviruses happen?

A

+strand RNA can be directly translated to enzymes needed for replication, then turned into -strand then turned into +strand progeny

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

How does replication of orthomyxoviruses and paramyxoviruses happen?

A

-strand segmented RNA, mature virion must carry a polymerase to produce +strand RNA

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

How does replication of reoviruses occur?

A

Double stranded RNA, virion must carry polymerase, partial assembly takes place earlier because dsRNA is a huge danger signal and must be hidden

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

How does replication of herpes occur?

A

dsDNA, DNA viruses can use host cell RNA polymerase

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

How are naked viruses released from cells?

A

During cell lysis after accumulation

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

What is tissue tropism and what is it dependent on?

A

Cell or tissue type that supports replication of a given virus, dependent on:
Cell receptors for virus
Proper cell transcription factors and replication co factors
Ability of cells to support viral protein synthesis
Presence or absence of local temp, ph, o2 tension, nonspecific factors in body secretions, digestive enzymes and bile

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

What is the sequence of virus spread?

A
  1. Implantation at portal of entry
  2. Local replication and local spread
  3. Dissemination from portal of entry
  4. Multiplication in target organs
  5. Shedding of virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do viruses disseminate from portal of entry?

A

Viremia through circulation - multiply in endothelial cells or fixed macrophages, diffuse through gaps, and are carried by migrating leukocytes
Neural via nerves

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

What is the incubation period?

A

Time between exposure to virus and onset of disease

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

What are the three determinants of viral pathogenesis?

A
  1. Accessibility of virus to tissue
  2. Virus susceptibility to host defenses
  3. Cell susceptibility to viral multiplication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does pathogenesis of a virus result from?

A

Viral disruption of normal cellular processes

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

What is the host shut-off phenomenon?

A

Viruses induce a shutoff of cellular protein synthesis towards a complete shift to viral protein synthesis, culminates in cell lysis and tissue destruction

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

What are four factors contributing to viral diversity?

A
  1. Mutation - subtle genetic change
  2. Recombination/reassortment - major genetic change
  3. Replication rate and number of progeny
  4. Selective pressure in host
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a quasi species?

A

A dynamic distribution of related genomes - some alive, some dead, some drug resistant, some not, etc

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

What are three types of viral recombination?

A
  1. Independent reassortment = antigenic shift - in viruses with segmented genomes
  2. Homologous recombination - template switching during RNA replication, common in RNA viruses and retroviruses (HIV)
  3. Breakage/rejoining - prevalent in DNA viruses and large RNA viruses (SARS)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are characteristic of orthomyxoviruses and what is one example?

A 
Influenza
Single -strand RNA 
Segmented genome allows reassortment 
Hemagglutinin and neuraminidase spikes
RNA dependent RNA polymerase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are two mechanisms that allow flu to alter its antigenic constitution?

A

Antigenic drift

Antigenic shift

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

What are basic characteristics of paramyxoviruses and what are some examples?

A 
Linear ssRNA, -sense 
Genetically stable, narrow host ranges 
Parainfluenza 
Mumps and measles 
Respiratory syncytial virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are basics of picornaviruses and what are some examples?

A

No enveloped, +ssRNA
Enteroviruses
Hepatovirus
Rhinoviruses

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

What are the basics of togaviruses and what are some examples?

A

Arthropod borne viruses
Alphaviruses
Rubivirus: rubella

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

What are the basics of flaviviruses and what are some examples?

A

Enveloped, +ssRNA

Yellow fever and dengue

35
Q

What kind of virus is hepatitis c and what are the basic features?

A

Hepacivirus

+ssRNA, enveloped

36
Q

What are the basics of bunyaviruses?

A

Enveloped, triple segmented -ssRNA

Four genera: bunyaviruses, phlebovirus, nairovirus, hantavirus

37
Q

What are the basics of arenaviruses?

A

Enveloped, segmented circular -ssRNA
Unique to tropical America
Contracted by contact with rodents

38
Q

What are caliciviruses and what are two examples?

A

+ssRNA, no envelope

Norwalk virus and hepatitis e

39
Q

What are the basics of filoviruses and what is an important clinical example?

A

Enveloped, linear -ssRNA

Ebola

40
Q

What are the basics of reoviruses and what do they include?

A 
Medium sized nonenveloped, icosahedral 
Linear segmented dsRNA
Include rotavirus (causes gastroenteritis) and Colorado tick fever (coltivirus)
41
Q

What are the basics of coronaviruses and what is an example?

A

Large, +ssRNA
Enveloped, contain surface spikes
SARS

42
Q

What capsid do DNA viruses have and what is the exception?

A

Icosahedral capsids

Pox virus - complex capsids

43
Q

Which DNA viruses have a lipid envelope?

A

Pox
Herpes
Hepadna

44
Q

Which two families doe the papovavirus combine?

A

Papilloma

Polyoma

45
Q

How do DNA viruses maximize their genome?

A

Multiple promoters
Alternative splicing
Code from both strands (papilloma from one strand)

46
Q

What are the phases of DNA virus replication and what happens in each?

A

Immediate early phase - genes expressed in absence of new protein synthesis, viral proteins that induce expression of others
Early gene expression - regulatory proteins that participate in viral genome replication
Late phase - structural components, not til after viral DNA synthesis starts, repression of early genes

47
Q

Which viruses use host DNA polymerase mediated viral DNA synthesis and what does it require? What might it cause?

A

Papilloma and parvo
Requires host cell in s phase
Might cause a transforming infection

48
Q

Which viruses use viral polymerase mediated DNA synthesis?

A

Adeno, herpes, pox

49
Q

What are four mechanisms of viral DNA replication and what is an example of each?

A
  1. Self priming (parvoviruses)
  2. Bi-directional (papovaviruses)
  3. Strand displacement (adenovirus)
  4. Rolling circle (herpes)
50
Q

What is the relative speed of cellular changes following hcmv infection compared to other viruses?

A

Slower than lots of others

51
Q

What are the types of infection by DNA viruses?

A

Acute infection

Persistent infection - includes chronic, latent, and slow

52
Q

What is the difference between the different types of persistent infection by DNA viruses?

A

Chronic - continuous production of low/moderate levels of virus
Latent - little or no viral gene expression, no virus produced
Slow - long incubation with low or undetectable levels of virus

53
Q

What is a transforming infection?

A

Viral gene products can alter growth regulation of infected cells, can lead to oncogenesis and malignant progression
Two stages - immortalization and other changes for malignancy

54
Q

Parvoviruses

A

Small linear single stranded DNA
No envelope
Require helper to replicate
Dependovirus - no disease in humans, requires coinfector

55
Q

Papovaviruses

A

No envelope
Icosahedral
Double stranded circular DNA
Only infects human cells
Papilloma virus - maintenance in differentiating cells, productive
viral replication in differentiated cells
Polyoma viruses - BK(causes renal disease and hemorrhagic cysts), JC(can cause PML), MCV

56
Q

Which types of hpv cause cancer? Which does the vaccine protect against?

A

16, 18, 31

6, 11, 16, 18

57
Q

Adenovirus

A

No envelope
Linear double stranded DNA
Respiratory disease, pink eye, hemorrhagic cystitis

58
Q

Herpesviruses

A

Envelope
Linear double strand DNA
Icosahedral

59
Q

Herpes disease associations

A 
HSV 1 & 2 - cold sore, genital
HHV 3 - varicella zoster
HHV 4 - Epstein Barr - mono, burkitts lymphoma
HHV 5 - CMV - birth defects, retinitis
HHV 6 - fever and rash 
HHV 8 - kaposi's sarcoma
60
Q

Acyclovir

A

Anti herpesviral drug
Only infected cells convert to pro form by phosphorylation
Guanine nucleotide analog that terminates DNA synthesis

61
Q

Hepadnavirus

A 
Hep b
Mixed single and double stranded DNA 
Reverse transcription step 
Restricted to liver cells
Infection can be cleared or persistent
Effective vaccine
62
Q

Pox virus

A

Variola virus - causes small pox

63
Q

What is contained in the nucleocapsid of a retrovirus?

A

Two copies of genome
Reverse transcriptase
Integrase

64
Q

What are the coding regions of a retrovirus?

A

Gag gene - core proteins
Pol gene - for reverse transcriptase, integrase, protease
Env gene - surface glycoproteins

65
Q

What kind of virus is a human T cell leukemia virus? HIV?

A

Delta retrovirus

Lentivirus

66
Q

Endogenous retroviruses

A

Not capable of replication

Indicated in autoimmune diseases

67
Q

HTLV1

A

Four additional regulatory genes
Infection through infected lymphocytes not free virus
Three major mechanisms of transmission: blood transfusion, sex, transplacental or breast milk
Infect cd4 cell
Causes adult T cell leukemia and HTLV1 associated myelopathy (HAM)
Less than 1% infected individuals will develop disease

68
Q

What is the predominant HIV Clade in the US?

A

HIV-1 M Clade B

69
Q

What is the retrovirus life cycle?

A 
Absorption
Entry
Reverse transcription 
Integration
Transcription
Translation
Assembly
Budding
70
Q

What is the virion structure of HIV/retroviruses?

A

Envelope has gp41 and gp120 from cleavage of gp161 on env gene
7 additional proteins encoded that act as gene regulators

71
Q

How does HIV enter the cell?

A

Gp120/gp41 requires binding to at least 2 coreceptors
Major receptor is CD4 (binds gp120)
Coreceptors are CCR5 (m tropic viruses - bind preferentially to macrophages, don’t form syncytia) and CXCR4 (t tropic, preferentially bind T cells, form syncytia) - gp120 binds first and exposes fusion domain on gp41, then ph dependent conformational change leads to fusion

72
Q

What are targets of antiretroviral drugs?

A 
Reverse transcriptase (NRTIs and NNRTIs)
Protease
Integrase
CCR5 coreceptors 
Fusion inhibitors
73
Q

What are some inappropriate uses of anti microbial drugs?

A

Use in animal feed

Over prescribed

74
Q

What is the difference between and antibiotic and an anti microbial drug?

A

Antibiotic from microorganisms that kills or inhibits growth of other microorganisms
Anti microbials comprise true antibiotics and synthetic drugs

75
Q

What is the difference between narrow spectrum, extended, and broad spectrum antibiotics?

A

Narrow - kills gram + but not gram -
Broad spectrum treats both - can lead to superinfection
Extended spectrum is extra broad

76
Q

What is the difference between empiric and definitive therapy?

A

Empiric - don’t fully know what the patient has, use broad spectrum drugs

77
Q

What are the differences in structure of gram + and gram - bacteria?

A

Gram+ has no outer membrane
Gram+ has much thicker cell wall of peptidoglycan
Gram+ have no periplasm - resistance enzymes can diffuse out

78
Q

What are sites of drug action in a bacterium?

A 
Cell wall
Inner membrane 
Transfer of C1 units to make bases, amino acids 
DNA synthesis
Transcription
Translation
79
Q

What are three causes of natural selectivity of bugs?

A

Drug accessibility
Target sites
Metabolism

80
Q

What are mechanisms by which bacteria acquire resistance?

A

Mutation
Transduction - single gene transfer, common among gram+
Conjugation - through pilus, mainly gram- but cross species can occur
Transformation - bacteria can release DNA that is absorbed into recipient cells

81
Q

What are the results of drug resistance?

A

Lower drug accessibility
Drug inactivation
Altered target
Increase in concentration of competing substrate

82
Q

What must you expose the bug to for effectiveness? In an immunocompromised patient?

A

Minimal inhibitory concentration

Minimal bacteriocidal concentration

83
Q

What are two examples of sanctuaries?

A

Heart valve

Synthetic prostheses

84
Q

What aspects of the micro environment affect antibiotic action?

A

Ph
Pus, hemoglobin
Oxygen

85
Q

What are situations in which prophylaxis with antibiotics is effective?

A

Prevention of specific infection
Dirty surgery - GI tract or head and neck
Cardiac surgery
Implantations of prostheses or surgery in patients who have them
Dental work on patients with rheumatic fever or valve lesions
Young children with sickle cell disease

86
Q

What are typical side effects of antibiotics?

A

Allergies

Renal toxicity and ototoxicity

Block 1 - Fundamental Principles (6 decks)

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