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sci oly > microbe mission 2 > Flashcards

microbe mission 2 Flashcards

1
Q

What are the parts of a bright-field microscope?

A
  • Eyepiece/ocular lens
  • Objective lenses
  • Condenser lens
  • Illuminator
  • Diaphragm
  • Stage
  • Focus knob

These components work together to magnify and illuminate the specimen.

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2
Q

What is the function of a bright-field microscope?

A

To transmit light through a specimen to create contrast against the background

This allows for the visualization of the specimen’s structure.

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3
Q

What type of image does a bright-field microscope provide?

A

High resolution images of the specimen’s structure with dark images against a light background.

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4
Q

How are specimens prepared for a bright-field microscope?

A

Specimens are stained to improve contrast and then mounted on a slide.

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5
Q

What are the parts of a phase contrast microscope?

A
  • Phase plate
  • Condenser annulus
  • Objective lenses
  • Eyepiece

These components enhance contrast in transparent specimens.

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6
Q

What is the function of a phase contrast microscope?

A

To enhance contrast in transparent specimens without staining.

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7
Q

What type of image does a phase contrast microscope provide?

A

High contrast images of transparent unstained specimens, allowing visibility of organelles.

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8
Q

How are specimens prepared for a phase contrast microscope?

A

No staining is required; specimens are simply placed on a slide.

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9
Q

What are the parts of a fluorescence microscope?

A
  • Excitation light source
  • Excitation filter
  • Emission filter
  • Objective lens
  • Fluorescent detectors
  • Beam splitter/dichroic mirror

These components work together to produce images based on fluorescence.

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10
Q

What is the function of a fluorescence microscope?

A

To study specific molecules using the fluorescence properties of certain molecules.

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11
Q

What type of image does a fluorescence microscope provide?

A

Images with bright fluorescence against a dark background.

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12
Q

How are specimens prepared for a fluorescence microscope?

A

By treating samples with fluorescent dyes that emit light upon excitation.

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13
Q

What are the parts of a transmission electron microscope (TEM)?

A
  • Emission gun
  • Condenser lens
  • Objective lens
  • Projector lens
  • Viewing screen/photographic film
  • Vacuum system

These components allow for high-resolution imaging of internal structures.

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14
Q

What is the function of a transmission electron microscope?

A

To transmit an electron beam through a thin sample to form a high-resolution image.

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15
Q

What type of image does a TEM provide?

A

High-resolution images showing detailed structures at cellular and subcellular levels.

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16
Q

How are specimens prepared for a transmission electron microscope?

A
  • Fixed with chemical agents
  • Embedded in resin or plastic
  • Sectioned into ultra-thin slices
  • Stained with heavy metals

This preparation is crucial for preserving structures and enhancing contrast.

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17
Q

What are the parts of a scanning electron microscope (SEM)?

A
  • Electron gun
  • Condenser lens
  • Scanning coils
  • Detector
  • Vacuum system
  • Monitor/computer system

These components allow for detailed 3D imaging of specimen surfaces.

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18
Q

What is the function of a scanning electron microscope?

A

To scan the surface of a specimen with a focused electron beam to create 3D images.

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19
Q

What type of image does an SEM provide?

A

High-resolution 3D images of the specimen’s surface.

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20
Q

How are specimens prepared for a scanning electron microscope?

A
  • Fixed to preserve structure
  • Coated with a thin layer of metal
  • Placed on a metal stub

This preparation enhances conductivity and image quality.

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21
Q

What are the uses of a bright-field microscope?

A
  • Structural observations of stained cells or tissues
  • Quantitative cell/colony counting
  • Examination of fixed and stained specimens
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22
Q

What are the uses of a phase contrast microscope?

A
  • Study live, unstained samples
  • Behavioral study of live organisms
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23
Q

What are the uses of a fluorescence microscope?

A
  • Localize and quantify specific molecules
  • Tracking molecular interactions or dynamics
  • Gene expression and protein localization
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24
Q

What are the uses of a transmission electron microscope?

A
  • Detailed ultrastructure of cells and organelles
  • Subcellular features
  • Identify viral particles or nanostructures
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25
Q

What are the uses of a scanning electron microscope?

A
  • Surface morphology and topography studies
  • Analyze surface interactions or adhesion
  • Material science and nanotechnology
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26
Q

What is the purpose of a scale bar in microscopy?

A

To estimate the size of a specimen corresponding to real-life size.

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27
Q

How do you calculate magnification?

A

Eyepiece magnification * Objective lens magnification.

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28
Q

How do you calculate resolution?

A

(0.61 * light wavelength in nanometers) / numerical aperture.

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29
Q

What is a Neubauer counting chamber used for?

A

To directly count cells in a liquid sample.

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30
Q

How do you determine cell count with a Neubauer counting chamber?

A

Concentration of cells = (number of cells counted * dilution factor * 10^4) / volume of counted area in mL.

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31
Q

What is the structure of bacteria?

A

Unicellular organisms with a simple structure.

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32
Q

What is the bacterial membrane composed of?

A
  • Phospholipid bilayer
  • Proteins
  • Lipopolysaccharides (in gram-negative bacteria)
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33
Q

What is the function of the bacterial cell wall?

A

Provides structural support and protection, maintains cell shape, and prevents osmotic lysis.

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34
Q

What are bacterial flagella used for?

A

Enable bacterial motility through rotation.

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35
Q

What are bacterial pili (plus) used for?

A
  • Genetic material transfer (conjugation)
  • Attachment to surfaces or each other
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36
Q

What are bacterial fimbriae?

A

Short hair-like structures used to attach to surfaces or host tissues.

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37
Q

What is the bacterial nucleoid?

A

Region within cytoplasm containing DNA.

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38
Q

What is the bacterial cytoplasm composed of?

A
  • Water
  • Enzymes
  • Ions
  • Small molecules
  • Ribosomes
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39
Q

What are bacterial gas vesicles used for?

A

Provide buoyancy to allow aquatic bacteria to float at specific depths.

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40
Q

What are endospores?

A

Highly resistant, dormant forms of bacteria encased in a tough coat.

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41
Q

What are archaea?

A

Microorganisms similar to bacteria but capable of surviving in extreme environments.

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42
Q

What is unique about the archaeal cell membrane?

A

Contains ether linkages and can be lipid monolayers or bilayers.

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43
Q

What is the archaeal cell wall composed of?

A
  • Pseudopeptidoglycan
  • Polysaccharides
  • Proteins
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44
Q

What are eukaryotic cells characterized by?

A

More complex structure with membrane-bound organelles.

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45
Q

What is the eukaryotic cell membrane composed of?

A
  • Lipid bilayer
  • Embedded proteins
  • Cholesterol
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46
Q

What are the organelles of the eukaryotic cell?

A
  • Mitochondria
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
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47
Q

What is the function of contractile vacuoles?

A

Maintain osmotic balance in some protists.

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48
Q

What are eyespots used for in some protists?

A

Detect light to help the organism orient itself.

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49
Q

What are carboxysomes?

A

Protein shells containing enzymes for carbon fixation.

50
Q

What is the structure of gram-positive bacteria?

A

Thick peptidoglycan layer with teichoic acids, no outer membrane.

51
Q

How do gram-negative bacteria differ from gram-positive bacteria?

A

Thin peptidoglycan layer with an outer membrane made of lipopolysaccharides.

52
Q

What characterizes acid-fast bacteria?

A

Cell wall made of mycolic acids, appears red/pink after staining.

53
Q

What is the gram stain procedure?

A

Distinguishes between gram-positive and gram-negative bacteria.

54
Q

What is a virus?

A

Unique microorganisms capable of infecting host organisms.

55
Q

What does a viral genome consist of?

A

Either DNA or RNA, can be single or double stranded.

56
Q

What is a capsid?

A

Protein shell that surrounds and protects the viral genome.

57
Q

What is an envelope in the context of viruses?

A

A lipid bilayer from the host cell that surrounds some viruses.

58
Q

What are spike proteins/glycoproteins?

A

Glycoproteins that recognize and bind to host cell receptors.

59
Q

What role do enzymes play in some viruses?

A

Contribute to replication in the host cell.

60
Q

What is a lipid culture/broth culture?

A

Bacterial culture method using nutrient-rich liquid medium.

61
Q

What is an agar culture/solid culture?

A

Bacterial culture method using gelatinous agar to isolate colonies.

62
Q

What are selective media?

A

Media that allow growth of specific bacteria while inhibiting others.

63
Q

What are differential media?

A

Media that allow many types of bacteria to grow with appearance changes.

64
Q

What are enriched media?

A

Media supplemented with extra nutrients for fastidious bacteria.

65
Q

What is selective media?

A

Media that allows certain types of bacteria to grow while inhibiting others.

Examples include MacConkey agar which differentiates based on lactose fermentation.

66
Q

What are enriched media?

A

Media supplemented with extra nutrients to support fastidious bacteria growth.

Examples include chocolate agar and blood agar.

67
Q

What are the phases of the bacterial growth curve?

A

Lag phase, log phase, stationary phase, death phase.

68
Q

What occurs during the lag phase of bacterial growth?

A

Bacteria adapt to the environment and prepare for growth without dividing.

69
Q

What characterizes the log phase of bacterial growth?

A

Bacteria divide at a constant rate, exhibiting exponential growth.

70
Q

What happens during the stationary phase of bacterial growth?

A

The rate of cell division slows and becomes equal to the rate of cell death.

71
Q

What is the death phase of bacterial growth?

A

The number of dying bacteria exceeds the number of new cells being formed.

72
Q

What is the plate count method?

A

A method for counting living bacterial cells by diluting and counting colonies on agar plates.

73
Q

How is optical density measured in bacterial cultures?

A

By measuring the cloudiness or turbidity of the culture using a spectrophotometer.

74
Q

What is the formula for bacterial population size?

A

Initial population size * e^(growth rate*time).

75
Q

Define bacterial growth rate.

A

r = (ln(population size) - ln(initial population))/t.

76
Q

List major classes of antibiotics.

A
  • Penicillin
  • Tetracyclines
  • Beta-lactams
  • Cephalosporins
  • Fluoroquinolones.
77
Q

What is the role of penicillins?

A

They target bacterial cell wall synthesis and are bactericidal.

78
Q

How do tetracyclines function?

A

They inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit and are bacteriostatic.

79
Q

What do beta-lactams do?

A

They inhibit transpeptidase enzymes to prevent cell wall synthesis and are bactericidal.

80
Q

What are cephalosporins?

A

A subclass of beta-lactams that have a broader spectrum of activity against bacteria.

81
Q

What is the mechanism of fluoroquinolones?

A

They inhibit bacterial topoisomerases to interfere with DNA synthesis.

82
Q

What is heat sterilization?

A

A bactericidal method that disrupts microbial structure and function using heat.

83
Q

What does UV radiation do to microorganisms?

A

It damages microbial DNA, preventing replication and transcription.

84
Q

Describe the process of filtration in microbial control.

A

A mechanical process that removes microorganisms by passing liquids through filters.

85
Q

What are the types of chemical sterilization?

A
  • Alcohols
  • Aldehydes
  • Halogens
  • Hydrogen peroxide
  • Phenolics.
86
Q

What are limitations of culture-based approaches to study microbes?

A

Microbes may require specific conditions to culture, behave differently in isolation, and may not reflect natural communities.

87
Q

What is binary fission?

A

Asexual bacterial cell division.

88
Q

What are the steps of binary fission?

A
  • Initiation
  • DNA unwinding
  • Pre-replication complex formation
  • Priming and polymerase binding
  • DNA strand elongation
  • Primer removal and ligation
  • Termination of replication
  • Cell division.
89
Q

What is the role of RNA polymerase in transcription?

A

It binds to the promoter and catalyzes RNA synthesis.

90
Q

What happens during the initiation phase of transcription?

A

RNA polymerase binds to the promoter, forming a transcription bubble.

91
Q

What occurs during the elongation phase of transcription?

A

RNA polymerase adds ribonucleotides complementary to the DNA template.

92
Q

Describe termination in transcription.

A

RNA polymerase encounters a terminator sequence, releasing the RNA.

93
Q

What is the lac operon?

A

An inducible system for lactose metabolism with genes for breakdown and uptake.

94
Q

How is the lac operon regulated?

A

By the lac repressor protein and the presence of allolactose.

95
Q

What is the trp operon?

A

A repressible system involved in tryptophan synthesis.

96
Q

How does the trp operon regulation work?

A

Tryptophan binds to the trp repressor, blocking RNA polymerase when levels are high.

97
Q

What is the endosymbiotic theory?

A

Proposes that mitochondria and chloroplasts evolved from prokaryotic ancestors.

98
Q

What are some adaptations of microbes to extreme environments?

A
  • Accumulation of sugars and amino acids
  • Changing lipid bilayer composition
  • Resistant spores or extremozymes.
99
Q

Describe the morphology of Escherichia coli.

A

Rod-shaped, 1-3 µm in length, gram-negative.

100
Q

What diseases are caused by Escherichia coli?

A
  • Diarrheal diseases
  • UTIs
  • Neonatal meningitis
  • Sepsis.
101
Q

What is Rickettsia rickettsii responsible for?

A

Causes Rocky Mountain spotted fever (RMSF).

102
Q

What are the characteristics of Mycobacterium tuberculosis?

A

Gram-positive, rod-shaped, and causes tuberculosis.

103
Q

What disease is caused by Rickettsia rickettsii?

A

Rocky Mountain spotted fever (RMSF)

RMSF involves widespread endothelial damage due to the invasion of endothelial cells.

104
Q

What type of bacteria is characterized as small, pleomorphic, gram-negative rods or coccobacilli?

A

Rickettsia rickettsii

It stains poorly and is 0.3–0.5 µm in width and 0.8–2.0 µm in length.

105
Q

What components are found in the outer membrane of Rickettsia rickettsii?

A
  • Lipopolysaccharides (LPS)
  • Surface proteins (OmpA and OmpB)

These components aid in adhesion and immune evasion.

106
Q

What is the primary method of transmission for Mycobacterium tuberculosis?

A

Droplets

It blocks phagosome-lysosome functions, replicating within macrophages.

107
Q

What are the key processes involved in the pathogenicity of Mycobacterium tuberculosis?

A
  • Invasion
  • Phagosomal arrest
  • Dormancy
  • Reactivation

These processes contribute to the development of tuberculosis.

108
Q

What type of bacteria is Microcystis aeruginosa?

A

Cyanobacteria

It forms harmful algal blooms that produce toxins (microcystins).

109
Q

What is the primary reproduction method for Microcystis aeruginosa?

A

Binary fission

Cells aggregate into colonies for protection and buoyancy.

110
Q

What is a characteristic feature of Staphylococcus aureus?

A

Arranged in characteristic grape-like clusters

It is golden-yellow due to carotenoid pigments.

111
Q

What virulence factor is associated with Staphylococcus aureus that provides antibiotic resistance?

A

mecA gene

This gene encodes an alternative penicillin-binding protein (PBP2a).

112
Q

What type of infections can Staphylococcus aureus cause?

A
  • Skin and Soft Tissue Infections
  • Sepsis
  • Endocarditis
  • Pneumonia
  • Toxic shock

These infections are a result of its virulence factors.

113
Q

What is the shape and gram classification of Helicobacter pylori?

A

Gram negative, spiral-shaped

It adheres to gastric epithelial cells and survives in the stomach by producing urease.

114
Q

What diseases are associated with Helicobacter pylori?

A
  • Gastritis
  • Peptic ulcer diseases
  • Gastric cancer
  • MALT lymphoma

These conditions arise from its colonization in the gastric epithelium.

115
Q

What is a unique feature of Pyrococcus furiosus?

A

Survives in geothermal environments at high temperatures (80–110°C)

It relies on fermentation and produces hydrogen gas.

116
Q

What type of organism is Methanococcus sp.?

A

Archaea

It reduces CO2 or converts acetate to generate methane.

117
Q

What type of life cycle does Plasmodium falciparum undergo?

A

Complex life cycle involving mosquitoes and humans

It causes malaria through various developmental stages.

118
Q

What is the reproductive method of Saccharomyces cerevisiae?

A

Asexual reproduction as budding

Yeast mating can also form ascospores.

119
Q

What type of reproduction does Nannochloropsis sp. exhibit?

A

Binary fission or sexual reproduction

It is a microalgae known for its high lipid content.

120
Q

What is the structure of Escherichia virus T4?

A

Icosahedral head with contractile tail

It has a lytic life cycle and infects E. coli.

121
Q

What type of virus is the Human Immunodeficiency Virus (HIV)?

A

Positive sense ssRNA retrovirus

It causes AIDS by infecting and destroying immune cells.

122
Q

What is the main characteristic of prions?

A

Misfolded proteins that induce misfolding of normal proteins

Prions do not have a nucleic acid genome.

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