chapter 6 Flashcards
Growth Requirements
Nutrients & Chemical Requirements
Oxygen Requirements:
Nitrogen Requirements:
Physical Requirements:
pH Requirements:
Water Requirements:
Associations & Biofilms:
Microbial growth refers to
an increase in population size rather than individual cell size.
Microbes require
carbon, oxygen, nitrogen, and hydrogen to build cellular structures.
Carbon sources:
autotrophs and heterotrophs
Autotrophs
Use inorganic carbon (CO₂).
Heterotrophs
Obtain carbon from organic compounds.
Energy sources:
Phototrophs: Use light energy.
Chemotrophs: Obtain energy from chemical reactions.
Electron sources:
Organotrophs and Lithotrophs
Organotrophs
Get electrons from organic molecules.
Lithotrophs
Get electrons from inorganic sources.
Oxygen Requirements:
Obligate aerobes:
Obligate anaerobes:
Facultative anaerobes: .
Aerotolerant anaerobes:
Microaerophiles:
Obligate aerobes:
Require oxygen.
Obligate anaerobes:
Oxygen is toxic to them.
Facultative anaerobes
Prefer oxygen but can grow without it.
Aerotolerant anaerobes:
Can survive in oxygen but don’t use it.
Microaerophiles
Require low levels of oxygen.
Nitrogen Requirements:
Essential for nucleotides and proteins.
Nitrogen fixation by certain bacteria is crucial for life on Earth.
Physical Requirements:
temp ph and water
how does temp play a role
Affects enzymes and membranes.
Psychrophiles
Cold-loving.
Mesophiles
Moderate temperatures (most human pathogens).
Thermophiles
Heat-loving.
Hyperthermophiles
Extreme heat.
Neutrophiles
Prefer neutral pH.
Acidophiles
Thrive in acidic environments.
Alkalinophiles
Live in alkaline environments.
Water Requirements:
Osmotic pressure: Affects water movement.
Hydrostatic pressure: Barophiles thrive under extreme pressure.
Antagonistic relationships:
One organism harms another.
Synergistic relationships:
Organisms benefit from living together.
Symbiotic relationships
Interdependent organisms.
Biofilms
Microbial communities that enhance survival.
Defined Media:
Exact chemical composition is known.
Complex Media:
Contains unknown compositions (e.g., yeast extract).
Selective Media:
Encourages growth of certain microbes while inhibiting others.
Differential Media
Helps distinguish between different microbes based on visible changes.
Anaerobic Media:
Supports the growth of anaerobes.
Transport Media:
Used to preserve specimens during transport.
Log Phase:
Rapid cell division and exponential growth.
Lag Phase
Microbes adjust to new conditions; no significant growth.
Stationary Phase:
Nutrient depletion slows growth; cell death equals cell division.
