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BM211 microbiology > Block D > Flashcards

Block D Flashcards

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Biology 101 flashcards
1
Q

respiratory viruses

A

influenza, rhinovirus, adenovirus, coronavirus.
Usually acquired by inhalation of droplets and replicated in the respiratory tract

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2
Q

enteric viruses

A

polio, rotaviruses, reoviruses, some adenoviruses.
Replicate in the gut, and cause gastric infections. Acquired by ingestion of faecal-contaminated material.

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3
Q

arboviruses

A

flaviruses, bunyaviruses and some rhabdoviruses. Infects insects that ingest vertebrate blood. Replicate in tissue of the insect and then transmitted to vertebrate host.

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4
Q

hepatitis viruses

A

all viruses that cause liver disease

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5
Q

sexually transmitted viruses

A

herpes simplex, papilloma viruses.

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6
Q

where do viruses replicate

A

only in certain types of cells or in whole organisms for which the virus has a tropism

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7
Q

what are the easiest viruses to grow

A

bacterial

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8
Q

what are the hardest viruses to grow

A

plant because study often requires growth of whole plant

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9
Q

what is titer

A

number of infectious units per volume of fluid

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10
Q

plaque assay

A

analogous to the bacterial colony; one way to measure virus infectivity
Plaques are clear zones that develop on lawns of host cells
Lawn can be bacterial or tissue culture
Each plaque results from infection by a single virus particle

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11
Q

what are naked viruses

A

viruses without membranes

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12
Q

what are capsids

A

nucleic acid packaged in protein coat found in virions

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13
Q

what are nucleocapsids

A

nucleic acid and protein packaged into a virus

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14
Q

what is lysozyme

A

enzyme that makes hole in cell wall, lyses bacterial cell

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15
Q

what is neuraminidases

A

enzymes that cleave glycosidic bonds, allows liberation of viruses from cell

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16
Q

virus replication

A

initiation- recognition, attachment, penetration, uncaring
replication- transcription, protein synthesis, genome replication, assembly
release- lysis and release, budding and release

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17
Q

epstein-barr virus

A

target cell= B cell
receptor= C3d complement receptor

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18
Q

HIV 1

A

target= helper T cell
receptor= CD4

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19
Q

rhinovirus

A

target= epithelial cell
receptor= ICAM-1

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20
Q

poliovirus

A

target= epithelial cell
receptor= immunoglobulin super family protein

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21
Q

herpes simplex virus

A

target= many cells
receptor= immunoglobulin super family protein

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22
Q

rabies virus

A

target= neuron
receptor= acetyl choline receptor

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23
Q

influenza A virus

A

target= epithelial cell
receptor= sialic acid

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24
Q

B19 virus (parvovirus)

A

target= erythroid precursors
receptor= erythrocyte P antigen

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25
Q

picornaviridae

A

virus= rhinovirus
viral attachment protein= VP1, VP2, VP3 complex

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26
Q

adenoviridae

A

virus= adenovirus
viral attachment protein= fibre protein

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27
Q

reovirdae

A

virus= reovirus, rotavirus
viral attachment protein= alpha-1, VP7

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28
Q

togavirdae

A

virus= semliki forest virus
viral attachment protein= E1, E2, E3 complex

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29
Q

rhabdovirdae

A

virus= rabies virus
viral attachment protein= G protein

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30
Q

orthomyxoviridae

A

virus= influenza A virus
viral attachment protein= HA

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31
Q

paramyxoviridae

A

virus= measles virus
viral attachment protein= HA

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32
Q

herpesviridae

A

virus= epstein-barr virus
viral attachment protein= gp350 and gp220

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33
Q

retroviridae

A

virus= HIV-1
viral attachment protein= gp120

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34
Q

what does it mean if the virus is smaller

A

its more dependent on host

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35
Q

where does DNA transcription occur

A

nucleus, except poxviruses

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36
Q

what is transcription regulated by

A

interaction of DNA binding proteins with regions of viral genome

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37
Q

what does genome replication initiate

A

transcription of late genes

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38
Q

what kind of energy conservation is DNA replication

A

semi-conservative

39
Q

where does RNA replication occur

A

cytoplasm, except influenza

40
Q

what can eukaryotic ribosomes not translate

A

polycistronic mRNA

41
Q

what is a virus

A

genetic element that cannot replicate independently if a living host cell

42
Q

what are virions

A

extracellular form of a virus, exists outside host and facilitates transmission from one host cell to another, contain nucleic acid genome surrounded by a protein coat

43
Q

phases of viral replication

A
  1. Attachment (adsorption of phage virion)
  2. Penetration of viral nucleic acid
  3. Synthesis of viral nucleic acid
    and protein
  4. Assembly and packaging of new viruses
  5. Cell lysis and release of new virions
44
Q

what is a permissive cell

A

host cell that allows the complete replication cycle of a virus to occur

45
Q

attachment and entry of Bacteriophage T4

A

Virions attach to cells via tail fibers that interact with polysaccharides on E. coli cell envelope. Tail fibers retract, and tail core makes contact with E. coli cell wall. Lysozyme-like enzyme forms small pore in peptidoglycan. Tail sheath contracts, and viral DNA passes into cytoplasm

46
Q

T4 genome

A

has a dsDNA genome that is circularly permuted and terminally redundant

47
Q

what is the restriction modification system

A

DNA destruction system, effective only against double-stranded DNA viruses

48
Q

what do restriction enzymes do

A

they leave DNA at specific sequences, modification of host’s own DNA at restriction enzyme recognition sites prevents cleavage of own DNA

49
Q

what modified base does T4 DNA contain

A

5-hydroxymethylcytosine, its DNA is resistant to virtually all known restriction enzymes

50
Q

what can the T4 genome be divided into

A

early, middle and late proteins

51
Q

T4 genome early and middle proteins

A

enzymes needed for DNA replication and transcription

52
Q

T4 genome late proteins

A

head and tail proteins and enzymes required to liberate mature phage particles

53
Q

replication of bacteriophage T4 early proteins

A

enzyme for the synthesis and glucosylation of the T4 base hydroxymethylcytosine, enzymes that function in T4 replisome, proteins that modify host RNA polymerase

54
Q

replication of bacteriophage T4 middle proteins

A

additional proteins that modify host RNA polymerase, production of viral proteins

55
Q

replication of bacteriophage T4 late proteins

A

synthesised later, include proteins of virus coat, typically structural components, synthesised in larger amounts

56
Q

packaging the T4 genome

A

packaging motor attaches to prohead, packaging motor is assembled, double-stranded DNA is pumped into head under pressure using ATP, after head is filled with DNA T4 tail, tail fibres and other components are added, packaging motor discarded

57
Q

what is virulent mode

A

viruses lyse host cells after infection

58
Q

what is temperate viruses

A

can undergo a stable genetic relationship within the host, but can also kill cells though lytic cycle

59
Q

what is lysogeny

A

state where most virus genes are not expressed and virus genome (prophage) is replicated in synchrony with host chromosome

60
Q

what is lysogen

A

a bacterium containing a prophage

61
Q

bacteriophage lambda

A

linear dsDNA genome, Complementary, single-stranded regions 12 nucleotides long at the 5′ terminus of each strand.
Upon penetration, DNA ends base-pair, forming the cos site, and the DNA ligates and forms double-stranded circle
When lambda is lysogenic, its DNA integrates into E. coli chromosome at the lambda attachment site (attλ)

62
Q

cI protein (the lambda repressor):

A

causes repression of lambda lytic events (Activates lysogeny)

63
Q

Cro repressor

A

controls activation of lytic events (represses lysogenic genes)

64
Q

transduction

A

transfer of DNA from one cell to another by bacteriophage due to mispackaging of the bacteriophage genome- drives bacterial evolution

65
Q

Generalized transduction

A

DNA from any portion of the host genome is packaged inside the virion

66
Q

Specialized transduction

A

DNA from a specific region of the host chromosome is integrated directly into the virus genome

67
Q

what is entamoeba histolytica

A

a pathogenic protist transmitted to humans primarily though contaminated water and food

68
Q

what is entamoeba histolytica disease called

A

amoebiasis

69
Q

entamoeba histolytica non-invasive infection

A

intestinal disease, diarrhea, ulcers in colon

70
Q

entamoeba histolytica invasive infection

A

extra-intestinal disease, abscess in liver, lung and brain

71
Q

balantidium coli

A

ciliated, intestinal human and swine parasite. infections caused by cysts, transmitted to humans through faecally contaminated water

72
Q

entamoeba histolytica treatment and diagnosis

A

azoles in particular metronidazole. cysts in stool

73
Q

balantidium coli treatment and diagnosis

A

tetracycline, metronidazole, iodoquinol. in stool and colon tissue

74
Q

Giardia intestinalis

A

Flagellated anaerobic parasite. Has mitosomes (mitochondrial 
remnant organelles). Produces highly resistant cysts
- Cause of giardiasis, a common waterborne disease. Explosive, foul-smelling diarrhea, 
intestinal cramps, nausea, weight 
loss, and malaise . Many individuals exhibit no 
symptoms and can act as carriers

75
Q

Giardia intestinalis diagnosis and treatment

A

cysts and trophozoites in faeces. metronidazole and tinidazole

76
Q

Trichomonas vaginalis

A

Flagellated anaerobic parasite.
Transmitted person-to-person by sexual intercourse. Can survive on moist surfaces:
Can be transmitted by toilet seats, sauna benches, 
and towels . Mostly asymptomatic in males . Vaginal purulent discharge, itching, and burning in women

77
Q

Trichomonas vaginalis diagnosis and treatment

A

microscopy and cell culture from patient secretions. metronidazole

78
Q

Cryptosporidium parvum

A

Protist (Apicomplexa) lives as a parasite in warm-blooded animals, causes diarrhoea.
Produces thick-walled cells (oocysts) that are shed in the faeces of infected animals
The oocysts are transmitted in faecally contaminated water (e.g. swimming pools)
Oocysts are highly resistant to chlorine 
and UV radiation; thus, sedimentation 
and filtration methods are most effective 
at removal

79
Q

Toxoplasma gondii

A

Apicomplexan protist that lives as a parasite in warm-blooded animals
Life cycle is similar to Cryptosporidium parvum with the same intermediate stages
Produces oocysts that are shed in the faeces of infected animals
The oocysts are transmitted by cats (also by undercooked meat)
Toxoplasmosis is mainly asymptomatic
Toxoplasma can damage eyes, brain, and other organs in
immune-compromised individuals
Toxoplasma can cause birth defects
Treatment: Sulphadiazine and Pyrimethamine; Spiromycin

80
Q

Naegleria fowleri

A

A free-living amoeba found in soil and water
Infections usually result from swimming in warm, soil-contaminated water sources (e.g., hot springs or lakes)
Enters the human body through the nose and 
burrows directly into the brain, causing extensive 
hemorrhage and brain damage (meningoencephalitis)
In most cases fatal

81
Q

Naegleria fowleri diagnosis and treatment

A

Diagnosis from cerebrospinal fluid
Drug treatment is only effective if infections are 
identified early. Azoles, amphotericin B, rifampicin, and 
miltefosine

82
Q

Acanthamoeba

A

Many species (e.g. castellani, polyphaga and culburtsoni)
found in fresh and salt water throughout the world
Infection through contaminated contact lenses/contact lens cases. Can also infect broken skin and cause cutaneous disease or even spread to the brain via the blood. Can also infect the mucosa and then the brain in a similar way to Naegleria
Disease caused:
- Eye Disease: Acanthamoeba keratitis (AK)
- Cutaneous Amoebiasis: Skin Disease
- Brain Disease: Granulomatous Amoebic Encephalitis (GAE)

83
Q

Acanthamoeba diagnosis and treatment

A

Diagnosis by microscopic examination of tissue samples
Treatment with azoles, amphotericin B, rifampicin, and 
miltefosine (same as for Naegleria)

84
Q

Acanthamoeba keratitis (AK)

A

Progressive sight-threatening corneal disease
The leading risk factor is contact lens wear
Most common type of Acanthamoeba infection
Treatment is not always successful and corneal transplants are often required
Reactivation often occurs in transplanted cornea

85
Q

Malaria

A

Caused by the apicomplexan parasite Plasmodium
Complex life cycle including Anopheles mosquitoes as vectors
~350 million people infected worldwide
Each year over 1 million people die from malaria
Generally found in tropical and subtropical regions

86
Q

Plasmodium and Malaria

A

Diagnosis requires identifying Plasmodium-infected erythrocytes 
in blood smears by microscopy
Drugs are used to prevent and treat infections
e.g. chloroquine and mefloquine (Lariam), pyrimethamine, doxycycline, clindamycin
Malaria may recur years after the primary infection
Several vaccines are currently in development
Can be controlled by draining swamps or eliminating mosquitoes

87
Q

Leishmania

A

Flagellated protozoan
Causes cutaneous, mucocutaneous 
or visceral leishmaniasis
Transmitted by bite of sand fly
Infects and grows in macrophages
Diagnosis: Microscopy of tissue specimen
PCR, serology

88
Q

Leishmania mexicana

A

Causes cutaneous leishmaniasis
Forms nodules and ulcers on skin
Treatment with pentavalent antimonial 
compounds, amphotericin B, miltefosine

89
Q

Leishmania braziliensis

A

Causes mucocutaneous leishmaniasis (South America)
Parasite destroys mucosa and cartilage of mouth, nose and throat
If untreated, mucocutaneous disease can be fatal
Treatment with pentavalent antimonial compounds, amphotericin B, miltefosine

90
Q

Leishmania donovani

A

Causes visceral leishmaniasis (VL)
Parasite travels to internal organs
Damage to liver, spleen, and bone marrow
If untreated, visceral disease is fatal
Recovery possible but occasionally relapse occurs (post-kala-azar dermal leishmanoid; PKDL)
Treatment with pentavalent antimonial compounds, amphotericin B, miltefosine

91
Q

Trypanosoma brucei

A

Two subspecies
T. brucei gambiense
T. brucei rhodesiense
Causes African sleeping sickness (Human African trypanosomiasis; HAT); 55 million at risk; 300,000 cases/year
Transmitted by bite of tsetse fly
Parasite multiplies in blood
Intermittent fever during early stages of infection (stage I)

92
Q

Trypanosoma brucei stage 2

A

Leeds to inflammation of brain tissue and necrosis
Diagnosis by spinal puncture and microscopy of cerebro-spinal fluid
Requires hospitalisation
Meningoencephalitic stage, invasion of the central nervous system with headaches, somnolence, abnormal behavior, lethargy, loss of consciousness and coma
Treatment with suramin, melarsoprol, pentamidine,
eflornithine

93
Q

Trypanosoma cruzi

A

Causes Chagas’ disease (American trypanosomiasis)
Transmitted by bite and defaecation of “kissing bug“ (Triatomine bug)
Parasite affects heart, gastrointestinal tract, and central nervous system
Occurs in Latin American countries
Diagnosis by microscopy or serology
Treatment with nifurtimox (Lampit) and benznidazole (Radanil)

BM211 microbiology (5 decks)

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