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Host and Defense > Week 1 > Flashcards

Week 1 Flashcards

1
Q

Name the three different types of capsids for viruses

A

Icosahedral
Helical
Complex

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2
Q

What are the three basic functions of a capsid?

A

Protect genetic material

Aid entry into cell

Package of viral enzymes

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3
Q

Icosahedral capsids are composed of repeating subunits Called ___. These subunits are each composed of 5-6 individual protein structures called ____

A

Capsomere

Protomer

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4
Q

What are ‘spikes’?

A

Glycoproteins embedded in the envelope of viruses that function to attach viruses to host cell membranes

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5
Q

What is tegument?

A

A layer of proteins between the envelope and capsid of enveloped viruses. It serves to attach the envelope to the capsid and can be involved with delivering viral genetic material/replication enzymes into cells.

It is polar

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6
Q

What is ambisense RNA?

A

Double stranded RNA that contains both positive and negative sense strands in the same dsRNA

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7
Q

True or false… positive sense RNA is oriented 3’-5’

A

False. It is oriented 5’-3’, meaning that it can be translated directly, thus is essentially mRNA

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8
Q

Which virus is more likely to contain RNA dependent polymerase? A virus containing negative sense RNA or positive sense RNA?

A

Negative sense

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9
Q

Under the ____ system of classification, viruses are grouped according to genetic material

A

Baltimore

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10
Q

Viruses have no means of locomotion, thus completely rely on ____ to reach cells

A

Collision

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11
Q

True or false… viruses often require coreceptors to enter a cell

A

True

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12
Q

Once the virus is inside of the cell is it considered to be in the ____ phase

A

Eclipse

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13
Q

Define uncoating

A

The process in which viral genetic material is placed into cells

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14
Q

What are the two different types of pathways in which enveloped viruses enter the cell? Also name three examples of viruses for each

A

Direct fusion: HIV 1, herpesviruses, paramyxovirus

Viropexis: influenza, rubella, rabies

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15
Q

In direct fusion, the ____ remains in the plasma membrane, allowing the ____ to enter the cytoplasm.

True or false… in direct fusion, the normal endocytic pathway doesn’t take place

A

Envelope

Nucleocapsid

True

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16
Q

Explain how viropexis works.

A

Basically receptor mediated endocytosis.

Here the envelope remains in fact as it crosses the plasma membrane. Once inside the cell the vesicles are in low pH environments then fuses with endosomal vesicles. (Normal endocytic pathway)

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17
Q

Describe how naked viruses enter the cell

A

Basically through viropexis except it must disrupt the endosomal vesicle because they have no envelopeto fuse with it.

The low pH in the vesicle will activate viral proteins which lyse the vesicles

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18
Q

What is a concatamer?

A

A series of repeated viral genomes. This is produced by the viral DNA folding in a way to allow replication to occur over and over again on the same DNA strand, allowing the generation of continuous RNA

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19
Q

What must occur to concatemers before viral genomic assembly?

A

Concatemers must be cleaved into single strand viral genomic DNA

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20
Q

List the steps for the parvirus (a DNA virus)

A

1) viropexis
2) host DNA polymerase 2nd strand synthesis
3) DNA replication within host cell cycle
4) mRNA generation via host RNA polymerase 2 during S phase
5) translation via host ribosomes
6) viral replication proteins return to the nucleus to pump up viral DNA replication and viral structural proteins
7) concatemers makes even more viral mRNA
8) concatemers breaks into single strand viral DNA
9) New progeny virus

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21
Q

Where do RNA + viruses typically reproduce?

A

In the cytoplasm

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22
Q

List the steps for a RNA + virus

A

1) RNA + virus enters cell and uses host ribosomes for direct translation of viral proteins
2) initial production of viral replication proteins and structural proteins in a large polyprotein precursor, which is cleaved into functional parts
3) viral RNA replication enzymes generate RNA - strand templates, which make more complementary viral RNA +
4) more viral structural proteins are transcribed
5) new progeny viruses are formed

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23
Q

How can RNA - viruses replicate in either the cytoplasm or the nucleus?

A

They bring their own enzymes (specifically RNA reverse polymerase, to form RNA +)

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24
Q

List the steps for RNA - virus

A

1) viral RNA - enters nucleus (or cytoplasm) and must utilize reverse RNA polymerase to create RNA + strands
2) complementary RNA + strands are produced using viral RNA reverse polymerase.
3) RNA + strands are either sent to the cytoplasm for translation in host ribosomes or retained and used as templates to replicate complementary viral RNA -
4) viral structural and replication proteins are transcribed
5) assembly of structural protein with RNA - (formation of new progeny viruses)

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25
Q

Describe the steps for a retrovirus

A

1) Viral RNA enters nucleus (or cytoplasm) and must use reverse transcriptase to create DNA from RNA template
2) viral RNA is reverse transcribed into DNA, using viral reverse transcriptase enzymes
3) viral DNA can replicate along with the normal cell cycle.
4) viral DNA is transcribed to form both viral mRNA and new viral RNA, using host cell machinery
5) viral mRNA is translated to form viral structural and replicative proteins
6) assembly of structural protein with viral RNA arising from reverse transcribed viral DNA
7) new virus progeny are formed

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26
Q

Define encapsidation

A

The insertion of individual viral genomes into individual capsids.

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27
Q

There is usually a site on the viral genome that codes for proteins intended to initiate assembly called ____

A

Packaging site

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28
Q

What is the most likely form of egression for naked viruses?

A

Cell apoptosis

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29
Q

What type of fungi is part of our normal flora?

A

Candida

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30
Q

Name three polysaccharides that make up the cell wall of fungi

A

Mannan
Chitin
B glucans

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31
Q

Instead of cholesterol, fungi have ____ in their membrane

A

Ergosterol

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32
Q

What drug destroys ergosterol?

A

Polyenes

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33
Q

What drug destroys the enzyme responsible for synthesizing ergosterol 14a-demthylase?

A

Azoles

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34
Q

What drug is responsible for targeting 1-3 B D glucan synthase in the fungal cell membrane?

A

Echinocandins

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35
Q

True or false…both yeasts and molds are always single cellular

A

False. Although yeasts are single cellular, molds are multicellular and filamentous

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36
Q

Describe what yeast colonies in culture look like

A

Single
Creamy, mucoid
Facultative anaerobes

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37
Q

Describe what mold colonies look like in culture

A

Fuzzy/velvety

Obligate aerobes

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38
Q

What is a blastoconidia?

A

A new bud that is budding off of a parent yeast cell

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39
Q

Strings of blastoconidia will form ____ whereas germ tubes will form ____.

A

Pseudohypha

Hypha

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40
Q

Usually yeast only form pseudohypha while mold form true hypha. What is the yeast that is the exception,
Because it can form both?

A

Candida

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41
Q

What are the two types of true hypha? Name a type of fungi of each type

A

Septate hypha - aspergillus

Nonseptate hypha - zygomycete

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42
Q

The sexual cycle in fungi is called ____

A

Sporulation

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43
Q

Yeasts reproduce by budding (asexual) only whereas molds can reproduce asexually and sexually. What is the term for the asexual state and the sexual state?

A

Asexual - anamorph

Sexual - telomorph

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44
Q

Describe asexual reproduction in fungi

A

Mitotic division of haploid nucleus

Yeast by budding

Molds by producing conidia, or by division of hypha elements

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45
Q

Describe sexual reproduction in fungi

A

Diploid nucleus divides by meiosis

Haploid nuclei of donor and recipient fertile cells fuse

Molds can also reproduce by producing spores

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46
Q

Define dimorphic fungi

A

Geographically restricted pathogens that exist as a mold at lower temperatures (environment) and a yeast at higher temperatures (body)

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47
Q

Name six dimorphic fungi species

A 
Blastomyces dermatitidis 
Coccidiodes immitis 
Histoplasma capsulatum
Paracoccidiodes brasiliensis 
Penicillium marneffei 
Sporothrix schenckii
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48
Q

Name sex examples of opportunistic fungi

A 
Aspergillus spp. 
Candida spp. 
Cryptococcus neoformas 
Mucor spp. 
Rhizopus spp. 
Pneumocystis jirovecii
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49
Q

Name four examples of cutaneous fungi

A

Malassezia furfur
Epidermyophyton spp.
Microsporum spp.
Trycophyton spp.

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50
Q

What are the three immunity strategies to fight off fungi?

A

Natural barriers
Innate immunity
Cell mediated immunity

Note that antibodies are not helpful in fighting off fungi

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51
Q

What are the gram stain results for yeast?

A

Yeasts stain gram positive (violet)

52
Q

What are the two most common species of candida?

A 
Candida albicans 
Candida glabrata (note that this species is resistant to fluconazole)
53
Q

True or false… candida species are part of our normal flora. If so, where are they found and what are some common infections?

What are some drug classes to treat candida diseases?

A

True

Skin, mouth, upper respiratory tract, bowels, vagina

Thrush, vaginitis, balanitis, diaper rash

Azoles (fluconazole), echinocandins (caspodungin), or polyenes (amphotericin).

54
Q

Rhinocerebral zygomycosis (also referred to as mucormycosis) are rare infections from what three genus types? These thrive in high _____ and ____ environments

A

Mucor, rhizopus, rhizomucor

Glucose

Acidic

55
Q

Rhinocerebral zygomycosis disease are ____ meaning that airborne spores are inhaled and can spread through vessels and facial planes

A

Angioinvasive

56
Q

True or false… candida species are yeast. Mucor and rhizopus species are also yeast

A

The first part is true, the second is false. Mucor and rhizopus species are zygomycete species.

57
Q

What is candidemia?

A

Systemic candidiasis

58
Q

Define pancytopenia

A

Deficiency of all three blood types (RBCs, White blood cells, platelets)

59
Q

Describe mycobacteria

A

Bacilli
Obligate aerobes
Cell wall - ‘waxy’ coat, high lipid content, mycolic acids, lipoarabinomannan

Acid fast bacilli (binds carbon fuchsin dye so that it is not removed by acid alcohol)

60
Q

What does it mean to be acid fast?

A

Resistance to decolonization by acid

61
Q

Name four tuberculous mycobacteria species

A

M. Tuberculosis (MTB)
M. Africanum
M. Bovis
M. Bovis bacille calmette-guerin (BCG)

62
Q

Name four non-tuberculous slow growing mycobacteria species

A

M. Kansasii
M. Valium-intracellulare complex
M. Marinum
M. Scrofulaceum

63
Q

Name two non-tuberculous mycobacteria rapid growing species, and one special grower

A

Rapid growers
M. Chelonae-abscesses complex
M. Fortuitum complex

Special grower
M. Leprae

64
Q

True or false… mycobacterium tuberculosis is transmitted via the respirator route. The respiratory droplets can remain suspended in air for several hours

A

True

65
Q

Which results in respiratory droplets being expelled the furthest and fastest, sneezing, coughing, or breathing?

A

Sneezing

66
Q

T cells will wall off the tuberculosis infection into a structure called a ____. _____ necrosis occurs here

A

Granuloma

Casteating necrosis

67
Q

TB remains in the latent phase but will go to the active phase usually about ___ years after exposure. When it becomes active, it will activate in the ___ portion of the lung

A

5-7

Superior apeces (because this is where the highest conc. Of oxygen exists).

68
Q

What is a Ghon complex?

A

A calcified focus of infection and associate lymph node

69
Q

In two step TST testing, what is the difference between the first and second test?

A

First test will test if the person has TB infection or not.

Second will test if the person has LTBI or not

70
Q

Besides a TB skin test, what is another method for testing if the patient has TB or not? Explain how it works

A

Interferon-gamma release assay

The APC processes antigen, APC presents antigen to T cell, T cell produces IFN-gamma

71
Q

In active TB, what is the difference between cavitation and milliary TB?

A

Cavitation is localized while milliary is spread

72
Q

Name three clinical features of active TB

A

Cough and production of sputum as tissue necrosis is one of the earliest signs

Dyspnea (aka shortness of breath) - a later symptom indicating extensive involvement parenchyma)

Fever and weight loss reflecting systemic actions of IL-1 and TNF-a secreted by activated macrophages

73
Q

True or false… the treatment and infection control measures for latent TB and active TB are the same

A

False, they are different

74
Q

True or false… sterile tissue/body tissue can be used to diagnose TB. CSF, bone, pleural fluid, and blood culture can be used

A

False… all these can be used besides blood culture

75
Q

True or false… AFB stains does not differentiate between MTB and NTM

A

True

76
Q

True or false… nucleic acid amplification tests can be used directly from sputum

A

True

77
Q

Describe the Ruyon classification system of NTM (non-tuberculous mycobacteria).

A

This is an old classification system, current identification by rRNA sequencing and/orMALDI-TOF MS

Groups based on rate of growth, production of yellow pigment, whether pigment is produced in the dark or only after exposure to light

78
Q

Name the four Runyon classes?

A

runyon 1 - photochromogens (slow growth, yellow pigment only when exposed to light)
runyon 2 - scotochromogens (slow growth, yellow pigment in light or dark)
runyon 3 - nonchromogenic (slow growth, no pigment.
runyon 4 - rapid growers (colonies in 5 days, no pigment)

79
Q

Where are rapid growers most likely to infect a host?

A

Skin and soft tissue as well as lung tissue

Note that these species are morphologically indistinguishable

80
Q

What is a sporotrichoid?

A

Lymphocutaneous infection

81
Q

Name two examples of Runyon class 4 species

A

M. Fortuitum

M. Chelonae-abcessus

82
Q

Describe M. Marinum

A

A slow grower
Photochromogen
Grows best 30-32 C
Traumatized skin in contact with water

83
Q

What is a scrofula?

A

Cervical lymphadenitis (slowly progressive)

84
Q

What does it mean if cervical lymphadenitis is…
Acute/bilateral
Acute/unilateral
Subacute or chronic unilateral

A

Acute/bilateral - viral upper respiratory tract infection or streptococcal pharyngitis

Acute unilateral - streptococcal or staphylococcal infection

Subacute or chronic unilateral - bartonella (cat scratch disease), or MYCOBACTERIA infection

85
Q

What runyon classification is M. Scrofulace?

A

Runyon 2

86
Q

M. Kansasii and M. Marinum are under what runyon classification?

A

Runyon 1

87
Q

Name some differences between lepromatous leprosy and tuberculoid leprosy

A

Lepromatous leprosy
Poorly demarcated, raised lesions. Sheets of foamy macrophages in the dermis containing very large numbers of bacilli (multibacillary)

Tuberculoid leprosy
Well demarcated lesions with central hypopigmentation and hypoesthesia. Granulmatous inflammation and rare acid-fast bacilli in the tissues (paucibacillary)

88
Q

True or false… bacterial infections are on the rise. Why?

A

True

Increasing number of immunocompromised patients, increase spread of antibiotic resistant bacteria, increasing international travel.

89
Q

True or false… bacteria are the oldest, most prevalent forms of life on earth

A

True

90
Q

Define pleomorphic

A

Lacking a distinct shape

91
Q

What is the bacteria morphology that is between vibrio and spirochete?

A

Spirillium

92
Q

What are the four phases to binary replication?

A

Lag phase
Log phase
Stationary phase
Death phase

93
Q

_____ ____ in biofilms allow bacteria to communicate

A

Quorum sensing

94
Q

What is periplasmic space?

A

This is the space in gram negative bacteria between the cell membrane and the outer cell membrane

95
Q

What bacteria do not have cell walls?

A

Mycoplasma

Acid-fast bacteria

96
Q

Respiratory chains, secretion systems, and adhesins are located in the bacterial cell membrane, true or false

A

False. These are located in the cell WALL

97
Q

Where would you find teichoic acid?

A

In the peptidoglycan cell wall of gram positive bacteria

98
Q

Binding of peptidoglycan to ____ or _____ can stimulate inflammatory responses

A

Toll-like receptor 2 or pattern recognition receptor

99
Q

In peptidoglycan, the peptide chains are attached to ____. Each peptide chain connects to another peptide chain by ____

A

NAM

Pentaglycine interbridge

100
Q

The binding of LPS by _____ or ____ can stimulate an inflammatory response

A

Pattern recognition receptor

Toll-like receptor 4

101
Q

The ____ on LPS is highly variable

A

O-chain

102
Q

True or false… you will be able to see ureoplasma and mycoplasma species in gram stain

A

False. Because these species have no cell wall

103
Q

If a bacterial species lacks a cell wall, what does it use to stabilize its cell membrane?

A

Sterols (cholesterol from hosts)

Note that these species will also be resistant to penicillin

104
Q

Name six factors associated with bacterial cell walls

A 
Electron transport chains
Protein secretion systems
Flagella
Adhesins
Capsules
Spores
105
Q

Describe facultative anaerobes

A

They prefer the presence of oxygen but can survive without it

106
Q

The drawback to oxygen is that it can produce toxic byproducts. Name two enzymes that are used to counter this issue.

A

Superoxide dismutase

Catalase or peroxidase

107
Q

What are secretion systems?

A

Usually found in gram negative species. They allow toxins or effector molecules to be injected into host cells or the environment.

108
Q

How do type 3, 4, 6, and 7 secretion system work?

A

It actually punctures a hole in the host cell and directly injects toxins to alter host cellular pathways

109
Q

How do type 1, 2, and 5 secretion systems work?

A

They deliver proteins like toxins or siderophores to the extracellular environment

110
Q

Flagellin is highly antigenic. It is known as the ___ antigen

A

H antigen

111
Q

What does lophotrichous mean?

A

This bacteria has a tuft of flagella on one side of the cell

112
Q

Describe axial filaments

A

Flagella present within the periplasmic space of spirochetes. This allows them to corkscrew their way through dense tissue. They often pick up host proteases on the way to aid in their penetration

113
Q

Bacterial ____ proteins are often associated with hair -like fibers called pili or fimbriae

A

Adhesin

114
Q

Type ___ pili is involved in conjugation

A

4

115
Q

True or false.. pili may be used for motility

A

True.

116
Q

Describe capsules. Also known as the ___ antigen

A

Layer of polysaccharide or polypeptide associated with the bacterial surface. Provides protection against phagocytosis, detergents, and antimicrobial peptides.

K antigen

(Capsules are opsonic)

117
Q

What is the difference between operons and regulons?

A

Operons are genes that code for multiple RNA.

Regulons regulate the transcription of operons

118
Q

True or false… there are no exons or introns in bacterial genes

A

True. It is an open reading frame

119
Q

Sigma factors are like transcription factors. Without them you will not get tight binding of ___ to the ___

A

RNA polymerase to the promoter

120
Q

What two methods do bacteria use to increase genetic diversity?

A

Mutation

Horizontal gene exchange mechanisms

121
Q

True or false.. regardless of the circumstances, bacteria do not change their ability to mutate

A

False. Some may become hypermutable in stressful environments

122
Q 
Out of the following bacteria,determine which are obligate aerobes, faculatative, microaerobes, or anaerobic.    
Neisseria
Pseudomonas
Legionella
Mycobacterium 
Most gram - species
Streptococcus 
Spirochetes 
Clostridium 
Bacteroides
A

Obligate aerobes: neisseria, pseudomonas, legionella, mycobacterium
Facultative anaerobes: most gram - negative rods, streptococcus
Microaerobes: streptococcus, spirochetes
Anaerobes: clostridium, bacteroides

123
Q

Name some features of streptococcus pneumoniae

A

Gram positive cocci in pairs

Catalase negative 
Bile soluble (substrate dissolves them)
124
Q

Name some features of Haemophilus influenzae

A

Gram negative pleomorphic

Only grows on chocolate agar

Requires X and V factors

125
Q

Name some features of pseudomonas

A

Non fermenting gram negative bacilli

Smells like corn chips

Oxidase positive

Produces pyocyanin

126
Q

Name some features of legionella species

A

Pleomorphic, gram negative bacilli

Host and Defense (17 decks)

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