Ch 4-5 Microbio Flashcards
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)
Distinguish between heterotrophy and autotrophy
-Heterotrophs: rely on organic (C containing) compounds made by other organisms
-Autotrophs: make their own organic compounds from carbon dioxide
Distinguish between photoautotrophy and chemolithoautotrophy
-Photoautotrophs: use light energy to capture and fix CO2 into organic molecules
-Chemo: use eneergy from mineral oxidation to capture and fix CO2 into organic molecules (litho-rock)
Distinguish between photoheterotrophy and chemoheterotrophy
-Photoheterotrophs: like chemo but also uses light energy to obtain energy
-Chemoheterotrophs: beak down organic substances to obtain energy and build biomass (humans are this)
Define nitrogen fixation in terms of its chemical input and output
Takes nitrogen gas (plus hydrogen) and converts it ammonia and hydrogen
Discuss ways to import nutrients into a cell across the cell membrane(s)
Diffusion (passive, facilitated) and active transport
Define facilitated diffusion
Occurs when molecules diffuse through membrane-spanning protein channels or pores
–>requires channel or pores as gateways
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
Define ABC transporter 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)
Define group translocation and how it works
Avoids uphill transport by chemically altering subtrate –> changed subtrate = starting subtrate not moving against concentration gradient any more
–> alteration requires energy
Define the function of a siderophore
Binds tightly to tiny amounts of soluble iron around and then imported into the cell
Give examples of molecules transported by the above pathways (active)
Glucose, amino acids, ions like Na and K
Describe the process of dilution streaking and its utility
A stick or loop carrying bacteria is spread across the agar surface, leaving cells behind
Describe how to make an agar Petri plate
A liquid culture or sample with bacteria is repeatedly diluted and spread on agar plates until single colonies are isolated
Describe a bacterial colony
A group of bacteria derived from the same mother cell
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
Define confluent growth
When cells or bacteria cover an entire surface area without gaps
Distinguish complex and synthetic media
-Complex: nutrient rich but poorly defined
-Synthetic: precisely defined ingredients
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
Describe a method to detect the presence of unculturable bacteria
Detect presence by extracting and sequencing DNA from the environment
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)
Define planktonic growth
Growth as isolated cells, often happens in shaking liquid culture
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.
Define generation time/doubling time
Time required for the population to double
Describe some of the culture conditions that can change generation time
Depends on the species and on the growth conditions (medium, temperature, shaking, etc.)
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
Define and order the 4 phases of bacterial growth in batch culture
- Lag: bacteria prepares cell machinery for growth (gearing up)
- Log: growth approximates an exponential curve (sprinting)
- Stationary: cells stop growing and shut down (stopping/break)
- Death: cells die with a “half life” similar to radioactive decay (negative exponential curve) (sleep/die)
Describe some of the physiological changes that take place in different growth phases
- Lag: bacteria prepares cell machinery for growth
- Log: growth approximates an exponential curve
- Stationary: cells stop growing and shut down
- Death: cells die with a “half life” similar to radioactive decay (negative exponential curve)
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.
Describe typical components of a bacterial extracellular matrix
Polysaccharides, proteins, and/or DNA
Briefly describe the stages of biofilm formation
- Attachment to monolayer by flagella
- Microcolonies
- Exopolysaccharide production
- Mature biofilm
- Dissolution and dispersal
Define endospore and mother cell
When species (i.e Bacillus and Clostridium genera) form endospores under starved conditions (survival cell)
–> form inside mother cell
–> complete formation results in mother cell dying
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
Define extremophile
An organism that thrives in extreme environmental conditions, such as high salinity, temperature, or pressure
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
Distinguish 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
Define barophile/piezophile
Organisms adapted to grow at high pressure (>1,000 atm), often found in deep-sea environments
Define osmotic pressure and why it is an issue for bacterial cells
-Pressure exerted by the movement of water across a membrane due to solute concentration differences.
-High osmotic pressure can cause cells to lose or gain water, impacting growth
Define halophiles
-Organisms that require high salt concentrations (2-4 M NaCl) for growth
-Counteracts osmotic pressure by importing potassium or producing compatible solutes
Distinguish between “philic” and “tolerant” species
-Philic: requires specific conditions for survival
-Tolerant: can survive but does not require extreme conditions
Distinguish neutralophiles, acidophiles, and alkaliphiles with respec to their preferred growth pH
-Neutral: 5-8 pH
-Acid: 0-5 pH
-Alkali: 9-12 ph
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
Distinguish strict anaerobes, strict aerobes, faculative 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
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
Define the parameters needed for effective sterilization via autoclaving
-Conditions: 121°C, 15 psi, >20 minutes
-Effective for sterilizing glassware, instruments, and media
Distinguish physical and chemical agents for microbrial 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.
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.
Define D-value
Time needed to reduce a microbial population by 90% under specific conditions
Briefly describe phage therapy
-Use of bacteriophages (viruses targeting bacteria) to kill pathogenic bacteria
-Phages are narrow-spectrum and specific to certain bacterial species
