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Micro final Flashcards

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1
Q

Define genome

A

The complete set of genetic material in an organism, essential for life functions

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2
Q

Distinguish between prokaryotes and eukaryotes

A

-Prokaryotes: No nucleus, smaller, include bacteria and archaea
-Eukaryotes: have a nucleus and organelles, larger in size

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3
Q

Describe Robert Hooke’s microscopic observations and contribution to biology

A

-Built first compound microscope
-Coined the terms cells with said microscope

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4
Q

Distinguish among bacteria, archaea, microscopic eukaryotes, and viruses

A

-Bacteria: single celled, no nucleus, found everywhere
-Archaea: similar to bacteria but thrive in extreme conditions
-Microscopic eukaryotes: fungi, algae, protozoa
-Viruses: non-living, require a host to replicate

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5
Q

Describe Antonie van Leeuwenhoek’s observations of bacteria

A

-First to observe bacteria using a single-lens magnifier

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6
Q

Describe the debate around spontaneous generation in the 1700s and how it was disproven by Francisco Redi and Lazzaro Spallanzani

A

SG debate: living creatures can arise spontaneously, without parents
-Redi: maggots come from flies, not meat
-Spallanzani: sealed boiled broth –> showed no microbial growth

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7
Q

Describe how Louis Pasteur finally laid to rest the theory of spontaneous generation

A

Swan-neck flask experiment confirmed microbes don’t arise spontaneously (even with access to oxygen)

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8
Q

Describe the germ theory of disease and contrast it with the four humors theory that dominated for millennia

A

-Germ theory: microbes cause infectious diseases
-Four humors: blood, yellow bile, black bile, and phlegm determine a person’s temperament (a deficit or imbalance in one causes sickness)

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9
Q

Describe methods to obtain a pure culture of a microbe, including the use of solid media

A

-Pure culture: use of solid media (agar plates) to isolate microbes
-Could also dilute sample into tubes until a tube only gets 0 or 1 bacteria in it

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10
Q

Describe Koch’s postulates defining the causative agent of a disease

A

Criteria for establishing that an infectious microbe is responsible for a
disease:
1. Microbe found in all cases of disease but not in healthy individuals
2. Microbe can be isolated from diseased host and grown in pure
culture
3. Introduction of the microbe into a healthy host will result in the
same disease
4. Microbe can be re-isolated from the newly diseased host, and
shows the same characteristics in culture

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11
Q

Describe a Winogradsky column and its relationship to microbial ecosystems

A

A whole microbial ecosystem is involved in cycling nutrients in the environment. This column demonstrates microbial ecosystems

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12
Q

Describe extremophiles and why they can be useful to humans

A

-Microbes living in extreme conditions (e.g., thermal vents)
-Importance: biotechnology and industrial applications

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13
Q

Define a microbiome and distinguish it from microbiota

A

-Microbiome: all microbes in an environment
-Microbiota: microbes specifically in or on the human body

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14
Q

Define resolution

A

smallest distance by which two objects can be separated and still be distinguished

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15
Q

Define millimeter, micrometer, and nanometer and the factors among them

A

-Millimeter (mm): 1mm = 1k micrometers
-Micrometer (µm): 1 µm = 1k nanometers
-Nanometers (nm): extremely small; used for viruses and molecular structures

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16
Q

Distinguish detection from resolution

A

-Detection: ability to perceive than an object exists, even if not resolved
-Resolution: ability to distinguish two separate objects CLEARLY

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17
Q

Define magnification and empty magnification

A

-Magnification: increases the apparent size of an object while enhancing resolution
-Empty mag: enlarges the image without adding info or detail

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18
Q

Identify and distinguish microbial shapes such as rods, filaments, cocci, spirals, and hyphal filaments

A

-Rods (bacilli): cylindrical shapes
-Cocci: spherical shapes; can form pairs (diplococci)
-Filaments: long, thread-like structures
-Spirals: spiral or corkscrew shapes
-Hyphal Filaments: branching filament structures, common in fungi

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19
Q

Describe light microscopy and how the wavelength of light is related to resolution

A

-Light microscopy: uses visible light to observe specimens
-Resolution improves with shorter wavelengths of light (blue light resolves finer details than red)

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20
Q

Describe the steps required to observe a specimen in a microscope

A
  1. Mount cells on a glass slide or holder
  2. Fix or immobilize the cells if necessary
  3. Apply stains (for certain microscopy types)
  4. Use immersion oil for higher resolution when applicable
  5. Focus the microscope using the stage and ocular lenses
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21
Q

Define reflection, refraction, and scattering

A

-Reflection: light bounces off object
-Refraction: light bends when passing through materials of different densities
-Scattering: light spreads after hitting an object smaller than its wavelength

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22
Q

Name ways to achieve contrast in both light and electron microscopy

A

-Light: use stains (simple or differential) or phase contrast techniques
-Electron: use metal coatings or cry-techniques

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23
Q

Distinguish between a simple stain and a differential stain

A

-Simple: adds uniform color to cells (e.g., methylene blue)
-Differential stain: distinguishes cell types (e.g., Gram stain, acid-fast stain)

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24
Q

Define brightfield microscopy and its pros/cons

A

-Light passes through stained specimens
-Pros: simple, effective for stained samples
-Cons: poor contrast for live, unstained cells
-Light background

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25
Describe darkfield microscopy and its pros/cons
-Detects scattered light; objects appear bright on dark background -Pros: no stains needed; good for small structures (flagella) -Cons: requires very clean samples
26
Describe phase-contrast microscopy and its pros/cons
-Exploits refractive differences to enhance contrast -Pros: good for live cells; no stains -Cons: limited to thin specimens -Dark cells on gray background
27
Describe differential interference contrast (DIC) microscopy and its pros/cons
-Uses polarized light for a 3D effect -Pros: good for live cells -Cons: complex setup -gray background with cells with both a light and dark edge
28
Describe fluorescence microscopy and its pros/cons
-Fluorescent dyes/proteins emit light at specific wavelengths -Pros: high specificity; multiple structures imaged -Cons: requires fluorescence labels -Glowing structures on black background -absorbs light at one wavelength and then re-emits light at a longer wavelength
29
Define super-resolution microscopy and its pros/cons
-Combine advanced techniques for finer detail -Pros: breaks light resolution limits -Cons: expensive and slow
30
Define transmission electron microscopy and its pros/cons
-Electrons pass through thin, stained sections -Pros: high resolution for internal structures -Cons: no live cells; labor intensive prep
31
Define scanning electron microscopy and its pros/cons
-Electrons scan sample surfaces; metal coated -Pros: high resolution 3D surface views -Cons: no internal details
32
Define cryo-electron microscopy and its pros/cons
-Samples frozen and imaged at cryogenic temperatures -Pros: preserves natural state; 3D tomography -Cons: expensive equipment
33
Define cytoplasm
Gel-like fluid inside the cell, containing water, enzymes, and biomolecules essential for life
34
Define nucleoid
Region in prokaryotes where DNA resides; not enclosed by a membrane
35
Define cell (cytoplasmic) membrane
Phospholipid bilayer that separates the cell's interior from the environment and regulates transport
36
Define cell wall
composed of peptidoglycan; provides shape, strength, and resistance to osmotic pressure (mesh bag)
37
Define outer membrane
Found in gram-NEGATIVE bacteria; contains lipopolysaccharides (LPS)
38
Define flagellum
helical structure enabling bacterial mobility, powered by proton motor force
39
Describe the chemical composition of bacterial membranes (cytoplasmic and outer) and the cell wall
-Cytoplasmic membrane: made of phospholipids and proteins –> semipermeable barrier -Outer membrane (gram-negative): Contains LPS [lipid A, core polysaccharide, o-antigen] -Cell wall: composed of peptidoglycan (glycan strands linked by peptide cross bridges)
40
Define the major components of the cytoplasm and their functions: DNA, mRNA, tRNA, ribosomes
-DNA: Genetic material encoding proteins -mRNA: messenger RNA transcribed from DNA for protein synthesis -tRNA transports amino acids to the ribosome for incorporation into a polypeptide -Ribosomes: translate mRNA into proteins
41
Describe the structure and properties of phospholipids and how this relates to membrane structure
-Structure: hydrophilic head (faces water) and hydrophobic tails (avoid water) –> form bilayers with hydrophobic cores
42
Describe the structure of the bacterial cell wall, its cellular function, and the roles of glycan strands and peptide cross bridges
-Structure: peptidoglycan (mesh bag) with glycan strands (NAG and NAM sugars) and peptide cross-bridges -Function: prevents lysis due to osmotic pressure and provides cell shape/rigidity
43
Define the cell envelope and describe the typical differences between gram +, gram -, and mycobacteria with respect to the cell envelope
-Gram POSITIVE: thick peptidoglycan layer with teichoic acids for additional strength -Gram NEGATIVE: thin peptidoglycan layer in the periplasm, surrounded by the outer membrane -Mycobacteria: thick cell wall with mycolic acids and phenolic glycolipids
44
Identify the components of lipopolysaccharide
-Lipid A: Anchors LPS. -Core polysaccharide: Sugar backbone. -O-antigen: Repeating sugar units, varies by strain
45
Define the periplasm
Space between the cytoplasmic and outer membranes in gram-negative bacteria; contains enzymes and transport proteins (cell wall resides)
46
Describe cell division and septation
-Cell division: cell wall synthesis is required for growth and division -Septation: formation of new poles during division
47
Describe different ways that bacterial cells grow
-Cocci: synthesize new hemispheres during division -Rods: elongate from sidewalls or grow from the tips
48
Describe the bacterial flagellum and flagellar motor
-Flagellum structure: helical filament of flagellin protein -Motor: rotates using proton motive force; can reverse direction
49
Define chemotaxis and briefly describe how it works to move bacteria towards an attractant via a "biased random walk"
-Movement toward chemical attractants via a “biased random walk” —>Run: straight movement when sensing an attractant (counterclockwise) —>Tumble: change direction when no attractant detected (clockwise) -Controlled by chemoreceptors in the membrane
50
Distinguish between macronutrients and micronutrients, giving examples of each
-Macronutrients: CHONPS make up the bulk of all living cells (carbohydrates, lipids, proteins, nucleic acids) —>Also include enzyme cofactors and signaling molecules like mg, fe, k, ca -Micronutrients: needed for enzyme function but in small (trace) quantities (Co, cu, mn, mo, ni, zn)
51
Define facilitated diffusion
Occurs when molecules diffuse through membrane-spanning protein channels or pores –>requires channel or pores as gateways
52
Define coupled transport, symport, and antiport and describe what powers them
-Coupled transport: moves molecule up gradient. Gets energy by coupling the movement of that molecule to a different molecule (ion) typically moving down gradient -Symport: both molecules are transported in same direction -Antiport: actively transported molecule moves from the opposite direction of the driving ion
53
Define ABC transporters and their power sources
ATP binding cassette are very large family of energy driven transport system found in all 3 domains of life –>use ATP to drive transport –>2 types: Uptake (nutrients in) and Efflux (toxins/drugs out)
54
Define group translocation and describe how it works
Avoids uphill transport by chemically altering subtrate –> changed subtrate = starting subtrate not moving against concentration gradient any more –> alteration requires energy
55
Define the function of a siderophore
Binds tightly to tiny amounts of soluble iron around and then imported into the cell
56
Give examples of molecule transported by active pathways
Glucose, amino acids, ions like Na and K
57
Describe the process of dilution streaking and its utlity
A stick or loop carrying bacteria is spread across the agar surface, leaving cells behind
58
Describe a bacterial colony
A group of bacteria derived from the same mother cell
59
Describe how dilution plates enable bacteria to be counted
Ensures that there are enough spaces on the plate for each bacterial cell to grow into a distinct colony that can be counted individually
60
Define confluent growth
When cells or bacteria cover an entire surface area without gaps
61
Distinguish complex and synthetic media
-Complex: nutrient rich but poorly defined -Synthetic: precisely defined ingredients
62
Define and distinguish selective and differential media
-Selective: favor the growth of one organism/strain over another -Differential: highlight phenotypic differences between two species that may grow equally well on the medium
63
Describe a method to detect the presence of unculturable bacteria
Detect presence by extracting and sequencing DNA from the environment
64
Describe and distinguish direct and indirect ways to count bacteria
-Direct: physically counted individual cells with a microscope -Indirect: estimate bacterial populations based on measurable parameters (light scattering)
65
Define planktonic growth
Growth as isolated cells, often happens in shaking liquid culture
66
Define growth rate and its relationship to population size
-Growth rate: percentage change in a population over specific period of time (average change in population over time) -Relates to population: positive growth rate = growing population.
67
Define generation time/doubling time
Time required for the population to double
68
Describe some of the culture conditions that can change generation time
Depends on the species and on the growth conditions (medium, temperature, shaking, etc.)
69
Identify the equation used to calculate doubling time
G = t/n
70
Define batch culture and distinguish it from continuous culture
-Batch culture: in a closed system like a flask -Continuous: fresh medium is constantly added and culture removed, so cells grow indefinately
71
Define and order the 4 phases of bacterial growth in batch culture
1. Lag: bacteria prepares cell machinery for growth (gearing up) 2. Log: growth approximates an exponential curve (sprinting) 3. Stationary: cells stop growing and shut down (stopping/break) 4. Death: cells die with a “half life” similar to radioactive decay (negative exponential curve) (sleep/die)
72
Describe some of the physiological changes that take place in different growth phases
1. Lag: bacteria prepares cell machinery for growth 2. Log: growth approximates an exponential curve 3. Stationary: cells stop growing and shut down 4. Death: cells die with a “half life” similar to radioactive decay (negative exponential curve)
73
Define a biofilm and give an everyday example of a biofilm
Group of cells secretes a sticky extracellular matrix that encases the population of cells. Examples include dental plaque.
74
Describe typical components of a bacterial extracellular matrix
Polysaccharides, proteins, and/or DNA
75
Briefly describe the stages of biofilm formation
1. Attachment to monolayer by flagella 2. Microcolonies 3. Exopolysaccharide production 4. Mature biofilm 5. Dissolution and dispersal
76
Describe the characteristics of spores
-Dehydrated = resistant to all sorts of environmental insults -Packed with small acid-soluble proteins (SASPs) to further protect their DNA
77
Define extremophile
An organism that thrives in extreme environmental conditions, such as high salinity, temperature, or pressure
78
Explain the relationship between growth rate and relative temperature
Growth rate increases with temperature up to an optimum, beyond which enzyme denature, slowing growth. –> Below the optimum, enzymes work more slowly, and membranes lose fluidity
79
Distinguish between psychrophile, mesophile, thermophile, and hyperthermophile with respect to their growth temperature ranges
-Psychrophiles: 0-20 °C -Mesophiles: 15-45°C -Thermophiles: 40-80°C -Hyperthermophiles: 65-121°C
80
Define barophile/piezophile
Organisms adapted to grow at high pressure (>1,000 atm), often found in deep-sea environments
81
Define halophiles
-Organisms that require high salt concentrations (2-4 M NaCl) for growth -Counteracts osmotic pressure by importing potassium or producing compatible solutes
82
Distinguish between philic and tolerant species
-Philic: requires specific conditions for survival -Tolerant: can survive but does not require extreme conditions
83
Distinguish between neutralphiles, acidophiles, and alkaliphiles with respect to their preferred growth pH
-Neutral: 5-8 pH -Acid: 0-5 pH -Alkali: 9-12 ph
84
Describe how alkaliphiles deal with having few protons to establish a proton motive force
Use sodium gradients across membranes instead of protons to power processes, as protons are scarce in alkaline
85
Distinguish between strict anaerobes, strict aerobes, facultative microbes, and microaerophiles
-Strict aerobes: require oxygen for growth -Microaerophiles: grow in low oxygen levels -Strict anaerobes: die in presence of oxygen -Facultative anaerobes: grow with or without oxygen -Aerotolerant: doesn’t use oxygen but can tolerate it
86
Distinguish among sterilization, disinfection, antisepsis, and sanitation with respect to controlling microbes
-Sterilization: kills all living organisms -Disinfection: kills/removes pathogens from inanimate objects -Antisepsis: kills/removes pathogens from living tissues -Sanitation: reduces microbial populations to safe levels
87
Define the parameters needed for effective sterilization via autoclaving
-Conditions: 121°C, 15 psi, >20 minutes -Effective for sterilizing glassware, instruments, and media
88
Distinguish physical and chemical agents for microbial control and give at least 2 examples of each
-Physical Agents: –>Autoclaving: High pressure and moist heat. –>Filtration: Removes microbes using 0.2 µm filters. Chemical Agents: –>Ethanol: Damages proteins and membranes. –>Chlorine: Oxidizes proteins and damages DNA.
89
Distinguish among different methods of pasteurization
-LTLT (Low Temp, Long Time): 63°C for 30 min. -HTST (High Temp, Short Time): 72°C for 15 sec. -Both eliminate pathogens like Coxiella burnetii but do not kill spores.
90
Define D-value
Time needed to reduce a microbial population by 90% under specific conditions
91
Briefly describe phage therapy
-Use of bacteriophages (viruses targeting bacteria) to kill pathogenic bacteria -Phages are narrow-spectrum and specific to certain bacterial species

OSU (17 decks)

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