Micro Chptr 7
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Microbial nutrition requires what three things?
- Chemical analysis
- Sources of essential nutrients
- Transport mechanisms
Bacteria are composed of different and , with and being the most .
elements; molecules; water; proteins; abundant
What percentage of bacteria is water?
What percentage of bacteria is proteins?
What is required for metabolism and growth?
Carbon and energy sources
What are two types of carbon sources?
What are heterotrophs?
- Organic molecules that depend on other life forms
- Ex: sugars, proteins, lipids
What are autotrophs?
- Inorganic molecules that feed themselves
- Ex: CO2
What is the most important growth factor?
Essential organic nutrients
What are some examples of essential organic nutrients?
Amino acids, vitamins
Why do scientist study microorganism's essential organic nutrients?
So they can grown them and kill them
What are 3 types of energy sources?
What do chemohetertrophs do?
- They can derive both carbon and energy from organic compounds
- Ex: Fungus that can break down dead things for energy & nutrients
What do Photoautotrophs do?
- They derive their energy from sunlight
- Ex: Algae, plants, some bacteria
What are the two types of chemoorganic autotrophs?
- Chemoorganic autotrophs
What do Chemoorganic autotrophs do?
- They derive their energy from organic compounds and their carbon source from inorganic compounds
- Ex: Methanogens
What do Lithoautotrophs do?
They neither rely on sunlight nor organics. They rely totally on inorganics
What are they 4 different transport mechanisms?
- Active transport
What is Osmosis?
A diffusion of water through a permeable but selective membrane. Water always moves towards higher concentration
What are the 3 different types of concentrations?
What is Isotonic?
Organism specified concentration
What is hypotonic?
Less concentration outside cell than inside causing cell to swell to dilute inside concentration
What is hypertonic?
Greater concentration outside the cell than inside causing the cell to shrink to dilute concentration outside of the cell.
What is diffusion?
Passive movement from high concentration to low concentration
What is Facilitated diffusion?
Passive transport of polar molecules and ions across the membrane
What is active transport?
Active transport of molecules against a gradient
What is the difference between active and passive?
Active requires energy and passive does not
What is Endocytosis?
- The active process of taking in substances without transporting them through the membrane. (common for eukaryotes)
- Ex: Phagocytosis, pinocytosis
What are the 6 environmental factors?
- Osmotic pressure
- Other factors
- Microbial association
What are Mesophiles?
- Organisms that thrive in 20-40 oC
- Ex: Humans and most microorganisms that attack us
What are Psychrophiles?
- Organisms that thrive in 0-15 oC
- Ex: Red snow organism
What are the 2 gases that most influence microbial growth?
What must happen to toxic metabolites for growth?
they must be neutralized
What are the 3 categories of bacteria?
- Obligate Aerobe
- Facultative Anaerobe
- Obligate Anaerobe
Which type of the 3 bacteria can exist in humans?
All 3 can exist in humans as pathogens
What is an Obligate aerobe?
- Bacteria that requires O2 for metabolism. Has enzymes to neutralize toxic metabolites
- Ex: most fungi, protozoa, and bacteria
What are Facultative anaerobes?
- Bacteria that does not require O2 but can grow in its presence
- Ex: Most Gram negative pathogens
What are Obligate anaerobes?
Bacteria that cannot use O2. The presence of O2 is toxic to the cell
What pH range do most cells grow best?
pH of 6-8
What are Halophiles?
- Bacteria that require high salt concentrations
- Ex: Halobacterium
What are Facultative halophiles?
- Bacteria that can survive in high salt conditions but is not required
- Ex: Staphylococcus aureus
What are some of the other environmental factors?
- Radiation- withstand UV, infrared
- Barophiles- withstand high pressures
- Spores and cysts- can survive anything (dry habitats)
What are 2 types of relationships microorganisms have?
What is a symbiotic relationship?
Relationship organisms have when they live in close nutritional environments
What are the 3 different types of symbiotic relationships?
What is a mutualism relationship?
relationship where both organisms benefit
What is a commensalism relationship?
Relationship where one organism benefits & other is not harmed
What is a parasitism relationship?
A host/ microbe relationship. One organism literally sucks the life out of the other
What is a non-symbiotic relationship?
Relationship where organisms are free-living and do not rely on each other for survival
Humans and microbes can have what type of relationships?
Commensal, parasitic, and synergistic (shared metabolism)
Microbial growth includes what steps?
- Binary fission
- Generation time
- Growth curve
- Enumeration of bacteria
What is binary fission?
The division of a bacterial cell through mitosis
What is generation time?
The time required for doubling
What 4 phases are there in the growth curve?
- Lag phase
- Log phase
- Stationary phase
- Death phase
What is the Lag phase?
Adjusting phase when microorganism first enters host
What is the Log phase?
Phase where maximum growth rate is reached for cell division
What is the Stationary phase?
Phase when cell goes into survival mode and # of cells that stop dividing= # of cells that continue dividing
What is the death phase?
Phase when majority of cells begin to die due to lack of nutrients
What is enumeration of bacteria?
- Processes used to count bacteria.
- Ex: Turbidity, Direct cell count, and automated devices
What is turbidity?
measurement of how cloudy test tube is. The greater the turbidity, the larger the population size
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