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Microbiology Flashcards

1
Q

Who wrote the first book dedicated to microscopic organisms?

A

Robert Hooke

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2
Q

What are the 4 Koch’s postulates?

A
  1. The suspected pathogen must be present in all cases of the disease and absent from healthy animals
  2. The suspected pathogen must be grown in pure culture
  3. Cells from a pure culture of the suspected pathogen must cause the disease in a healthy animal.
  4. The suspected pathogen must be reisolated and shown to be the same as before.
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3
Q

What are the 4 types of light microscopy?

A

Bright field
Phase contrast
Dark field
Fluorescence

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4
Q

What is differential interface contrast microscopy?

A

A form of light microscopy, which uses polarised light to make structures appear 3D

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5
Q

Describe atomic force microscopy

A

Measures forces between a probe and the atoms on the surface of the specimen, measures deviations from the flat surface

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6
Q

Describe confocal scanning laser microscopy

A

Couples a laser force to a fluorescent microscope, reconstructs the layers of the specimen to make it 3D, cells are typically dyed with fluorescent stains

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7
Q

Describe transmission electron microscopy

A

High magnification
0.2nm resolution
Can see molecular level structures
Need thin specimens as electrons don’t penetrate tissues well

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8
Q

Describe scanning electron microscopy

A

Shows external surfaces of the cell
Intact specimen is coated with a film of a heavy metal, like gold
Electrons scatter from the metal coating and are collected to form the image

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9
Q

What are endospores?

A

Highly differentiated cells, produced by some bacteria, resistant to harsh environments and used as a survival structure

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10
Q

Describe the process of sporulation

A
  1. An essential nutrient is exhausted
  2. Vegetative cell stops growing
  3. Endospore develops within cell and is released
  4. Remains dormant and germinates into a vegetative cell when conditions are favourable
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11
Q

What structure enables cells to stick to surfaces and each other?

A

Fimbriae

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12
Q

What structure enables conjugation between cells, mobility, and adhesion of pathogens to host tissues?

A

Pili

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13
Q

Name the 2 kinds of microorganism taxis

A

Chemotaxis and phototaxis

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14
Q

Describe flagella structure

A

Helical
Different wavelength for different species
Filament composed of many flagellin proteins

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15
Q

How do flagella move?

A

A molecular membrane embedded motor
Proton movement across the MOT complex in the membrane gives energy
Protons exert electrostatic forces on helically arranged charges on the rings that make up the motor
Attraction and repulsion causes rotation

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16
Q

Name the 3 kinds of flagella attachment points

A
  1. Polar flagellation
  2. Tuft
  3. Peritrichous
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17
Q

What are the 2 mechanisms known to be involved with gliding in microorganisms?

A
  1. Polysaccharide slime - slime adheres and pulls the cell along
  2. Twitching motility - repeated extension and retraction of type IV pili
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18
Q

What kind of bacteria can form multicellular structures, and what are these structures?

A

Myxobacteria

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19
Q

How do myxobacteria move?

A

They glide - leaving slime behind

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20
Q

Where do chemolithotrophs get their energy?

A

Inorganic chemicals

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21
Q

Define nitrogen fixation

A

Converting atmospheric nitrogen gas into a form usable by cells

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22
Q

What enzyme catalyses nitrogen fixation?

A

Nitrogenase

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23
Q

What is nitrogenase composed of?

A

Dinitrogenase
Dinitrogenase reductase

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24
Q

What reaction does nitrogenase catalyse?

A

Converting nitrogen into ammonia:
N₂ + 8H⁺ + 8e⁻ → 2NH₃ + H₂

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25
What is the second step in the nitrogen cycle?
Nitrification
26
Describe nitrification
Oxidation of ammonium into nitrites NH2 or NH3 by nitrifying bacteria
27
What are the 2 kinds of nitrifying bacteria?
Nitrosomonas Nitrobacter
28
What is denitrification?
The conversion of nitrates (NO₃⁻) back into nitrogen gas (N₂) by denitrifying bacteria, releasing it into the atmosphere.
29
What is humus?
Complex mixture of organic materials that have resisted rapid decomposition, derived primarily from plants and microorganisms
30
Give the basic steps of binary fission
1. Cell replicates DNA 2. Cytoplasmic membrane elongates 3. Cross wall septum forms 4. 1 parent cells forms 2 daughter cells
31
Define bacterial growth
The increase of cells within a population
32
What are the 3 ways of measuring bacterial growth?
1. Microscopic counts 2. Viable counts 3. Spectrophotometry
33
What does benthic mean?
Attached to the bottom or sides of the lake or stream
34
What are typical characteristics of microbes living in the ocean?
Very small cells - require less energy for maintenance Need greater number of transport enzymes to acquire nutrients
35
List 7 abiotic growth factors
Light pH Temperature Oxygen Pressure Moisture Nutrient availability
36
What are the minimum, maximum, and optimal temperatures called?
The cardinal temperatures
37
What does aerotolerant mean?
Anaerobic but can tolerate oxygen However, they do not use oxygen in their metabolism
38
What are microaerophiles?
Aerobes that can only use O2 when it’s present a levels lower than air
39
Define extremophile
An organism whose growth is dependent on extremes of temperature, salinity, pH, pressure, or radiation, which are generally inhospitable to most forms of life
40
What is a halophile?
Requires NaCl for growth
41
Define halotolerant
Can tolerate NaCl, but grows best in absence of a solute
42
Define psychrophile
Grows at extremely low temperatures
43
What was Waksman's original (1930) definition of an antibiotic?
A compound produced by a microbe to destroy other microbes.
44
What is an antimicrobial?
A compound that kills or inhibits microbes, including bacteria, fungi, and viruses.
45
What is the modern definition of an antibiotic?
A chemical compound with a single mode of action, effective only against bacteria.
46
Who discovered penicillin and when?
Alexander Fleming in 1928.
47
How did antibiotics impact mortality?
Significantly reduced deaths from infections, including childbirth-related deaths.
48
What does a bacteriostatic antibiotic do?
Inhibits bacterial growth without killing the bacteria.
49
What does a bactericidal antibiotic do?
Kills bacteria without lysing them; reduces viable cell count.
50
What does a bacteriolytic antibiotic do?
Kills bacteria by lysing the cell membrane; reduces total and viable cell count.
51
What are the advantages of narrow-spectrum antibiotics?
Target specific bacteria, lower resistance risk, less microbiome disruption.
52
What are the disadvantages of narrow-spectrum antibiotics?
Require accurate and fast diagnosis.
53
What are the advantages of broad-spectrum antibiotics?
Can be used before identifying the pathogen.
54
What are the disadvantages of broad-spectrum antibiotics?
Higher resistance risk and disruption of normal microbiota.
55
What is the mode of action of β-lactams?
Inhibit bacterial cell wall synthesis (bactericidal).
56
Give examples of β-lactam antibiotics.
Ampicillin, Cephazolin, Imipenem.
57
What are common side effects of β-lactams?
Allergic reactions.
58
What do sulfonamides target?
Dihydropteroate synthase (blocks folate synthesis, bacteriostatic).
59
Example of a sulfonamide drug?
Sulfamethoxazole (with Trimethoprim).
60
Common side effects of sulfonamides?
Hypersensitivity, insomnia, blood disorders.
61
How do fluoroquinolones work?
Inhibit DNA gyrase/topoisomerase IV (bactericidal).
62
Give examples of fluoroquinolones.
Ciprofloxacin, Norfloxacin, Moxifloxacin.
63
Side effects of fluoroquinolones?
Tendon damage, blood sugar fluctuations.
64
What is the action of macrolides?
Inhibit protein synthesis (bind 50S subunit, bacteriostatic).
65
Give examples of macrolides.
Azithromycin, Clarithromycin, Erythromycin.
66
Common side effects of macrolides?
Arrhythmias, liver toxicity.
67
What is the mode of action for tetracyclines?
Inhibit protein synthesis (bind 30S subunit, bacteriostatic).
68
Examples of tetracyclines?
Doxycycline, Minocycline, Tetracycline.
69
Side effects of tetracyclines?
Tooth discoloration, photosensitivity, liver toxicity.
70
How do aminoglycosides work?
Inhibit protein synthesis (bind 30S, bactericidal).
71
Give examples of aminoglycosides.
Streptomycin, Gentamicin, Neomycin.
72
Side effects of aminoglycosides?
Kidney toxicity, hearing loss, neuromuscular blockade.
73
Why can’t antibiotics treat viral infections?
They only act on bacteria.
74
When might antibiotics still be used during a viral infection?
To treat secondary bacterial infections.
75
What factors affect antibiotic dosage?
Age, weight, liver/kidney function, infection severity.
76
Why might IV antibiotics be used instead of oral?
Some antibiotics aren’t absorbed well orally.
77
Why should treatment duration be carefully managed?
Too short = ineffective, too long = resistance/side effects.
78
What % of antibiotics are used in livestock?
0.64
79
Why are antibiotics used in agriculture?
Disease prevention, growth promotion, feed efficiency.
80
What is the consequence of agricultural antibiotic use?
Increased antibiotic resistance.
81
What contributes to antibiotic misuse?
Overuse, incomplete courses, poor diagnostics, hospital hygiene.
82
Why has Big Pharma reduced antibiotic development?
High R&D cost ($1.5B), low returns ($46M/year), restricted use.
83
What is the 'post-antibiotic era'?
A time when antibiotics may no longer be effective due to resistance.
84
Name 3 WHO priority resistant bacteria.
Acinetobacter baumannii, Pseudomonas aeruginosa, E. coli.
85
How are new antibiotics being discovered?
Genome sequencing, resistance gene screening.
86
What are AMPs (antimicrobial peptides)?
Natural defense peptides, broad-spectrum, but toxic to humans.
87
What is an example of an anti-virulence drug?
Sibofimloc (blocks E. coli adhesion).
88
What are combination therapies in antibiotics?
β-lactams + β-lactamase inhibitors.
89
What is bacteriophage therapy?
Viruses targeting specific bacteria; requires personalized matching.

Organisms and environment (12 decks)

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