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Microbiology-HH3 > Structure, Function, Reproduction and Classification of Micro-organisms > Flashcards

Structure, Function, Reproduction and Classification of Micro-organisms Flashcards

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Biology 101 flashcards
1
Q

Symbiotic Associations?

A

symbiotic organisms live in close nutritional relationships with one another

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2
Q

Symbiotic Associations: Commensalism?

A

host is not harmed, nor benefits

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3
Q

Symbiotic Associations: Mutualism?

A

both members benefit

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4
Q

Symbiotic Associations: Parasitism

A

parasitic microbe depends on host; host is harmed

disease can result

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5
Q

Which symbiotic association can cause disease?

A

parasitism, relationship is causing harm to the host

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6
Q

Bacteria?

A

prokaryotic, no nuclei, single celled, lives in pairs, chains, clusters

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7
Q

Why are humans so sensitive to bacteria?

A

bacteria is prokaryotic and humans are eukaryotic, identify bacteria as foreign

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8
Q

Viruses?

A

Acellular, not visible by microscope, microbes made of genetic material surrounded by protein coat

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9
Q

Can viruses make proteins? how do viruses make proteins?

A

can’t make their own proteins, they must infect the cell of a host to make proteins

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10
Q

Do viruses reproduce or replicate?

A

replicate

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11
Q

Is algae harmful to humans?

A

no

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12
Q

Fungi?

A

eukaryotic, has a nuclei, cell wall, organelles, obtain nutrients from other organisms

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13
Q

2 examples of fungi?

A

yeasts and molds

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14
Q

Which microbe is most like humans?

A

fungi, both eukaryotic. few differences then us.

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15
Q

Why do humans not handle anti fungal agent well?

A

because fungi is like us, few agents to destroy them

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16
Q

Protozoa?

A

eukaryotic, single celled, has a nuclei

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17
Q

What is more destructive and harmful to humans’ viral infections or bacterial infections?

A

bacterial, more severe

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18
Q

Example of a protozoa?

A

parasites

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19
Q

Helminths?

A

eukaryotic, multicellular, has a nuclei, visible with naked eye

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20
Q

What microbe is visible to us with our aged eye? examples?

A

helminths. tape worms

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21
Q

order these 3 microbes based on size, protozoan, virus, bacteria (small to large)

A

small- virus, bacteria, protozoan- large

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22
Q

Shape of bacterial cell?

A

rod shaped

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23
Q

What organelle of a bacterial cell is a good target for antibiotics?

A

ribosomes

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24
Q

Plasmid’s function of a bacterial cell?

A

carry info about resistance to a host or resistance to an antibiotic
“DNA”

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25
Q

Function fo a cell wall?

A

provides structure

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26
Q

Characteristics of bacterial cells?

A

no nucleus, smaller DNA particles as “plasmids”, ribosomes are smaller than those of eukaryotic , cell wall and cell membrane, flagella and pili

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27
Q

How are bacterial infections exploited?

A

using antibiotics, to exploit the difference b/w prokaryotic and eukaryotic cells without damaging the host’s cells

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28
Q

How to classify bacterial cells based on morphology?

A

shape, arrangement, colony morphology, external structures, capsules and spore formation

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29
Q

How to classify bacterial cells based on cell wall structure?

A

staining and microscopy; gram and acid fast stain

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30
Q

How to classify bacterial cells based on growth characteristics?

A

oxygen and energy requirements

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31
Q

How to classify bacterial cells based on metabolism?

A

carbohydrate utilization, fermentation products

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32
Q

How to classify bacterial cells based on molecular techniques?

A

DNA sequencing

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33
Q

Bacterial cell morphology: diplococci, streptococci, staphylococci, bacilli, coccobacilli?

A 
diplococci= 2 round Paris
cocci= round
streptococci= grows in pairs and chains and always gram positive
staphylococci= gram positive, grows in clusters
bacilli = grows in rods
coccobacilli= more rounder rods
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34
Q

What allows for tentative bacterial classification?

A

letting the bacteria grow on agar plates to allow for characteristic development

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35
Q

What is a flagella?

A

protein filaments that extend from cell membrane

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36
Q

Function of the flagella?

A

rotate 360 degrees for movement in response to stimuli, whip like motion

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37
Q

Flagella:
polar=?
spirillium=?
peritrichous?

A 
polar= 1 flagella
spirillium= 2 flagella
peritritious= multiple flagella
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38
Q

Fimbriae?

A

straight filaments from cell wall of bacteria
shorter than flagella
not used for propulsion

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39
Q

Function of fimbriae?

A
  • “pulls” the bacterium

- acts as adhesions binding to a specific host cell

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40
Q

Conjugation pili function?

A

used to transfer DNA from one bacteria to another

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41
Q

Bacteria: glycocalyx?

what is it made out of?

A

-protective substance surrounding some bacteria
acts as a force shield
-made from polysaccharides
-presence/ absence can be used for classification

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42
Q

Function of glycocalyx?

A

helps bacteria avoid phagocytosis

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43
Q

2 types of glycocalyx

A
  • slime layer: prevents dehydration, allows bacteria to bind to surfaces and form a protective layer
  • capsule: attached to cell wall, facilitates adherence and impairs phagocytosis
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44
Q

Endospores?

A
  • defensive strategy against unfavourable environmental conditions
  • resistant to heat, cold, chemicals and radiation
  • wait it out until environment changes to what it needs to survive and grow
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45
Q

How to destroy endospores?

A

sterilization (steam, under pressure, chemical sterilants)

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46
Q

Bacterial cell wall function?

A
  • provides structure
  • maintains shape
  • protects from pressure
  • plateform for flagella and fimbriae
  • contributes to adherence
  • target for antibiotics (adhere to the cell wall)
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47
Q

Gram stain function?

A

-purple stain on bacteria to determine whether the bacteria is gram negative or gram positive

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48
Q

Gram positive?

Gram negative?

A 
G+= purple, retain the purple stain
G-= red, does not retain the purple stain
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49
Q

Why does gram positive retain the purple stain and why does gram negative bacterium not?

A 
gram positive (purple) bacterium have a thick, non porous cell wall
gram negative (red) bacterium have a thin cell wall with an outer membrane
50
Q

What does a gram negative bacterium have gram positive bacterium do not have?

A

outer cell membrane

51
Q

What does gram negative bacterium have in their cell membrane?

A

Lipid A (endotoxin)

52
Q

Human body and lipid A?

A

all immune systems recognize lipid A and causes inflammation, fever, vasodilation and can induce shock and blood clot formation

53
Q

Most hospital acquired infections are from?

A

gram negative bacterium

54
Q

Where is there a large number of gram negative bacterium? gram positive bacterium?

A
  • hospitals

- communities

55
Q

Safranin?

A

pink stain, gram negative bacterium will retain this giving it a red appearance

56
Q

What is the effect of human error when mishandling a gram-positive bacterium species?

A

looses cell wall integrity, stains as “gram negative” (red)

57
Q

Can some non-bacterial organisms with thick cell walls stain gram-positive?

A

yes

58
Q

Clinically, why is gram staining important

A

important for classifying bacterial pathogens, which is critical for choosing a treatment method

59
Q

What does a large amount of neutrophils mean?

A

bacterial infection is present

60
Q

Acid fast stain?

A

differential bacterial stain that distinguishes b/w organisms with a waxy cell wall (retains the stain)

61
Q

When to use acid fast stain? Example?

A
  • when mycobacterial infections are suspected

- TB (waxy cell wall)

62
Q

Bacterial classification based on oxygen requirements?

A
  • used to figure out last name of organism

- oxygen is a free radical and very dangerous to bacterial species, make it hard to survive

63
Q

3 Enzymes that bacteria uses to detoxify reactive oxygen products

A
  1. catalase
  2. peroxidase
  3. superoxidase dismutase
64
Q

Bacterial obligate aerobes organisms?

A
  • need oxygen to survive

- have all 3 enzymes in order to survive

65
Q

Microaerophiles?

A

-species that tolerate low amounts of oxygen

66
Q

Facultative anaerobes?

A

-prefer to grow in oxygen but can produce in environments that are oxygen deprived

67
Q

Fewer enzymes produced=?

A

less likely that those species tolerate oxygen

68
Q

Obligate anaerobes?

A
  • can’t tolerate oxygen
  • lack of enzymes
  • susceptible to damage as they don’t produce enzymes
69
Q

Bacteria reproduction; Asexual

  • Exponential phase?
  • Stationary phase?
  • Death phase?
  • Lag phase?
A
  • binary fission
  • EP= number of cells grow exponentially as nutrients are available
  • SP= nutrients deplete, toxic waste accumulates which slows growth rate
  • DP= no new sources of nutrients causes bacteria to die
  • LP= new environment, bacteria have to adapt and get used to environment prior to expanding
70
Q

How long does it take to identify a specimen based on growth rate?

A

48hrs hours

71
Q

What does bacteria sexual reproduction require?

A

conjugation pili

72
Q

Obligate intracellular bacteria?

A
  • need a host to survive
  • cant make their own energy
  • grow in cell cultures
73
Q

Facultative intracellular bacteria?

A
  • avaoid phagocytosis
  • reproduce and grow within immune cells
  • shield from antibodies and immune defences
  • mechanisms to defend against lysosomal enzymes produced by phagocytic cells
  • takes longer for body to identify infection
74
Q

Greater risk for infection with obligate or facultative intracellular bacteria?

A
  • facultative, b/c it can survive phagocytosis and avoid antibodies
  • greater risk for infection
75
Q

Viruses; obligate intracellular pathogen?

A
  • can’t replicate independently
  • need host cells to replicate
  • uses host cells energy, organelles, enzymes to replicate
76
Q

Viruses; acellular pathogens?

A
  • lack a cell membrane
  • only have a few organelles
  • DNA and RNA housed in a capsid
  • capsid has recognition sites that bind to receptors on host and it helps to protect the DNA and RNA
77
Q

Virus “envelopes”

A
  • some acellular viruses have this
  • allows for entry into a host cell
  • replaces cellular membrane proteins with virus derived proteins making entry into host cell easier
78
Q

Capsid?

A
  • protein coat protecting DNA and RNA

- has recognition sites on it to help bind to host cells

79
Q

Are viruses acellular or cellular?

A

acellular, b/c they are not “alive”

80
Q

What 4 characteristics of viruses are used to classify them?
What are more detailed characteristics of viruses used to classify them?

A
  1. vision structure
  2. mechanism of replication
  3. nature of genome
  4. molecular techniques
    - cytopathic effect on host cells
    - nature of disease
    - serological reactions
    - AA sequences of proteins, nucleic acid sequences
81
Q

Viral replication

A
  • can’t reproduce by itself
  • lack enzymes for replication
  • don’t have ribosomes for protein synthesis
  • when host cell is controlled by viral genome, viral genetic material is replicated and proteins are translated
82
Q

5 steps of viral replication: 1. Attachment

A
  • interaction with host cell receptor
83
Q

5 steps of viral replication: 2. Entry (3 ways)

A
  • direct penetration
  • membrane fusion
  • endocytosis
84
Q

What happens to viruses capsule after penetration?

Do you need capsule intact for entry?

A
  • sheds/ “uncaring”
  • need this to allow for replication
  • yes, you need capsule intact for entry
85
Q

5 steps of viral replication: 3. Synthesis (DNA and RNA)

A
  • DNA synthesis occurs in nucleus

RNA synthesis occurs in cytoplasm

86
Q

5 steps of viral replication: 4. Assembly

A
  • once synthesized, they are assembles into virions
87
Q

Virion?

A
  • entire virus particle
88
Q

5 steps of viral replication: 5. Release from host cell (budding and lysis/exocytosis)

A 
budding= visions are extruded through cell wall membranes, forming viral envelope
exocytosis= vision is extruded without acquiring an envelope
lysis= virus released by host cell, killing the host cell
89
Q

Aborted viral infection?

A
  • little or no detectable effect

- can be nothing if body does not recognize it or you are not exposed enough

90
Q

Persistent viral infection?

A
  • alterations of antigenic specificity of cell surface due to the presence of viral glycoproteins
  • host cell is intact so you get gradual, prolonged release of viral particles
  • HEP B (chronic infections)
91
Q

Latent viral infection?

A
  • viral genome is persistent in cell

- can be reactivated at anytime

92
Q

Transformation viral infection?

A
  • viral genome integration in host cell may disrupt host cell growth, replication and metabolism
  • result is tumour production
93
Q

Viral infection; host cell death?

A
  • rapid lysis of host cells and release of progeny

- feel “sick”

94
Q

Examples of persistent, latent and transformation viral infections?

A
  • Hep B
  • Cold sores
  • HPV, cervical cancer
95
Q

Fungi

A
  • grow as single cell or multicellular
  • most are not pathogenic (saprophytic)
  • identified by direct examination or in lab cultures
96
Q

Where do most fungi get their food from (saprophytic)?

A
  • dead organic matter
97
Q

Example of a single celled fungi?

A
  • yeast
98
Q

Example of a multi celled fungi?

A
  • mold
99
Q

Dimorphic fungi?

A

-can grow in both single celled or multicellular forms

100
Q

Hyphae?

A

-gives mold its fuzzy appearance

101
Q

How do yeasts reproduce?

A

budding

102
Q

How do molds and dimorphic fungi reproduce?

A
  • form asexual spores

- spores germinate to make new organisms once an ideal environment is found

103
Q

Cell wall; fungus vs bacteria

A
  • fungus cell wall= made of chitin

- bacteria cell wall= made of peptidoglycan

104
Q

Cell membrane; fungus vs humans

A
  • fungus= ergosterol

- humans= cholesterol

105
Q

Difference b/w ergosterol and cholesterol and anti fungal agents?

A
  • difficult to find the difference, thus anti fungal agents can cause many adverse affects
106
Q

Mycoses?

A
  • chronic fungal infections
  • grow slowly
  • classified into 5 categories
107
Q

Mycoses; Superficial infections

A
  • outermost layer of skin, hair, nails

- treat topically

108
Q

Mycoses; Cutaneous infections

A
  • deeper, keritonized skin layers
  • itchy, scaling skin, inflamed
  • topical therapy may not work
109
Q

Is cutaneous fungal infection transmissible?

A
  • yes
110
Q

Examples of cutaneous fungal infections?

A
  • ringworm, tinea
111
Q

Mycoses; Subcutaneous infections

A
  • dermal layer, subcutaneous layer, muscle layer as well
  • sessions of the skin
  • difficult to treat, excision or amputation is often needed
112
Q

Mycoses; Systemic infections

A
  • primary infection
  • start in lungs then travel into blood stream
  • associated with inhaled spores
  • found in feces of birds and bats
113
Q

Mycoses; Opportunistic infections

A
  • in people with impaired host defences

- AIDS, DM, cancer, immunosuppressive therapies

114
Q

Parasites?

A
  • develop in poor sanitation country’s
  • most common in tropical country’s (food and water)
  • 70% of people in the world are infected with a parasite
  • long chronic infections, can be serious
115
Q

Protozoa?

A
  • eukaryotic
  • unicellular
  • doesn’t have a cell wall
  • exist in a feeding state
  • form spores that protect from harsh environments
116
Q

Protozoan cyst?

A
  • thick capsule, low metabolic rate
  • infective form
  • protects from harsh environments
117
Q

Trophozoite?

A
  • active form

- can replicate and grow

118
Q

Site of infection for protozoans?

A
  • GI
  • UG tracts
  • Blood
  • Tissues
119
Q

Mode of locomotion for protozoans? (amoebas, flagellates, ciliates, sporozoa)

A

Amoebas- extend cytoplasmic projections outward from body to move
Flagellates- whip-like projections rotate and propel
Ciliates- hair-like projections on cell surface move in unison to move the cell
Sporozoa- non-motile, adult males can have a flagella

120
Q

Protozoan reproduction

A
  • asexual (binary fission)

- some is by sexual reproduction

121
Q

How do parasites gain access to human hosts

A
  • via ingestion or penetration (bite), attachment, replication and host damage

Microbiology-HH3 (6 decks)

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