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Chapter 7
Microbial Nutrition
71
Microbiology
Not Applicable
10/20/2016

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Term
Nutrition
Definition
process by which chemical substances (nutrients) are acquired from the environment and used in cellular activities
Term
Essential nutrients
Definition
Essential nutrients must be provided to an organism; Two categories of essential nutrients: macronutrients, micronutrients (or trace elements)
Term
Macronutrients
Definition
required in large quantities; play principal roles in cell structure and metabolism Proteins - nitrogen, carbohydrates - carbon
Term
Micronutrients (or trace elements)
Definition
required in small amounts; involved in enzyme function and maintenance of protein structure; Manganese, zinc, nickel; nutrients
Term
Organic nutrients
Definition
contain carbon and hydrogen atoms and are usually the products of living things; Methane (CH4), carbohydrates, lipids, proteins, and nucleic acids
Term
Inorganic nutrients
Definition
atom or molecule that contains a combination of atoms other than carbon and hydrogen; Metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water
Term
Chemical Analysis of Cell Contents
Definition
70% water; Proteins; 96% of cell is composed of 6 elements: Carbon, Hydrogen, Oxygen, Phosphorous, Sulfur, Nitrogen
Term
Heterotroph
Definition
must obtain carbon from an organic form made by other living organisms; proteins, carbohydrates, lipids, and nucleic acids
Term
Autotroph
Definition
uses CO2 (inorganic gas) as its carbon source; not nutritionally dependent on other living things
Term
Growth factors
Definition
Organic compounds that cannot be synthesized by an organism because they lack the genetic and metabolic mechanisms to synthesize them; Growth factors must be provided as a nutrient; Essential amino acids, vitamins, nucleotides
Term
Nutritional types
Definition
Main determinants of nutritional type are: Carbon source – heterotroph, autotroph;Energy source -Chemotroph – gain energy from chemical compounds;Phototrophs – gain energy through photosynthesis
Term
Photoautotrophs
Definition
Oxygenic photosynthesis; Anoxygenic photosynthesis
Term
Chemoautotrophs
Definition
lithoautotrophs survive totally on inorganic substances; methanogens, a kind of chemoautotroph, produce methane gas under anaerobic conditions
Term
Chemoheterotrophs
Definition
Aerobic respiration; two categories: saprobes and parasites
Term
Saprobes
Definition
free-living microorganisms that feed on organic detritus from dead organisms; Opportunistic pathogen; Facultative parasite
Term
Parasites
Definition
derive nutrients from host; Pathogens; Some are obligate parasites
Term
Passive Transport
Definition
does not require energy; substances exist in a gradient and move from areas of higher concentration toward areas of lower concentration; Diffusion; Osmosis – diffusion of water; Facilitated diffusion – requires a carrier
Term
Active Transport
Definition
requires energy and carrier proteins; gradient independent; Active transport; Group translocation – transported molecule chemically altered; Bulk transport – endocytosis, exocytosis, pinocytosis
Term
Diffusion
Definition
Net Movement of Molecules Down Their Concentration Gradient (Passive Transport)
Term
Osmosis
Definition
Diffusion of Water (Passive Transport)
Term
Isotonic solution
Definition
Water concentration is equal inside and outside of the cell, thus rates of diffusion are equal in both directions
Term
Hypotonic solution
Definition
Net difussion of water is into the cell; Cell membrane: causes cell to swell and may burst if there is no mechanism to remove the water; Cell wall: swells the protoplast and pushes it tightly against the cell wall, preventing the cell from bursting
Term
Hypertonic solution
Definition
Water difuses out of the cell; Cell membrane: causes it to shrink and become distoreted; cell wall: causes plasmolysis(shrinks the cell membrane away from the wall)
Term
Facilitated Diffusion
Definition
Requires a carrier(Passive transport)
Term
Carrier-mediated active transport
Definition
Atoms or molecules are transported into or out of the cell by specialized receptors, driven by ATP or other high energy molecules
Term
Group translocation
Definition
transported molecule is chemically altered
Term
Endocytosis
Definition
bringing substances into the cell through a vesicle or phagosome (bulk transport); Phagocytosis, pinocytosis
Term
Phagocytosis
Definition
ingests substances or cells(bulk transport)
Term
Pinocytosis
Definition
ingests liquids(bulk transport)
Term
Niche
Definition
totality of adaptations organisms make to their habitat
Term
Environmental factors
Definition
Environmental factors affect the function of metabolic enzymes; Factors include: Temperature, Oxygen requirements, pH, Osmotic pressure, Barometric pressure
Term
3 Cardinal Temperatures
Definition
Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism; Maximum temperature – highest temperature that permits a microbe’s growth and metabolism; Optimum temperature – promotes the fastest rate of growth and metabolism
Term
3 Temperature adaptation groups
Definition
Psychrophiles, Mesophiles, Thermophiles
Term
Psychrophiles
Definition
optimum temperature below 15oC; capable of growth at 0oC
Term
Mesophiles
Definition
optimum temperature 20o-40oC; most human pathogens
Term
Thermophiles
Definition
optimum temperature greater than 45oC
Term
Gas requirements
Definition
Oxygen:As oxygen is utilized it is transformed into several toxic products: Singlet oxygen (1O2), superoxide ion (O2-), peroxide (H2O2), and hydroxyl radicals (OH-); Most cells have developed enzymes that neutralize these chemicals: Superoxide dismutase, catalase; If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats; Carbon dioxide: All microbes require some carbon dioxide in their metabolism
Term
Aerobe
Definition
utilizes oxygen and can detoxify it
Term
Obligate aerobe
Definition
cannot grow without oxygen
Term
Facultative anaaerobe
Definition
utilizes oxygen but can also grow in its absence
Term
Microaeriphilic
Definition
requires only a small amount of oxygen
Term
Anaerobe
Definition
does not utilize oxygen
Term
Obligate anaerobe
Definition
lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment
Term
Aerotolerant anaerobes
Definition
do not utilize oxygen but can survive and grow in its presence
Term
Capnophile
Definition
grows best at higher CO2 tensions than normally present in the atmosphere
Term
Neutrophiles
Definition
Majority of microorganisms grow at a pH between 6 and 8
Term
Acidophiles
Definition
grow at extreme acid pH
Term
Alkalinophiles
Definition
grow at extreme alkaline pH
Term
Barophiles
Definition
can survive under extreme pressure and willl rupture if exposed to normal atmospheric pressure
Term
Symbiotic
Definition
two organisms live together in a close partnership; mutualism, commensalism, parasitism
Term
Mutualism
Definition
obligatory, dependent; both members benefit
Term
Commensalism
Definition
commensal member benefits, other member neither harmed nor benefited
Term
Parasitism
Definition
parasite is dependent and benefits; host is harmed
Term
Nonsymbiotic
Definition
organisms are free-living; relationships not required for survival
Term
Synergism
Definition
members cooperate to produce a result that none of them could do alone
Term
Antagonism
Definition
actions of one organism affect the success or survival of others in the same community (competition), antibiosis
Term
Normal flora(microbes and humans)
Definition
symbiotic bacteria, fungi, and a few protozoa
Term
Biofilms
Definition
result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers; Dominate the structure of most natural environments on earth
Term
Quorum sensing
Definition
Communicate and cooperate in the formation and function of biofilms
Term
Microbial growthoccurs at two levels:
Definition
growth at a cellular level with increase in size, and increase in population
Term
Division of bacterial cells occurs mainly through:
Definition
binary fission
Term
Binary fission
Definition
Parent cell enlarges, duplicates its chromosome, and forms a central transverse septum dividing the cell into two daughter cells
Term
Generation or doubling time:
Definition
Time required for a complete fission, can vary from minutes to days
Term
Exponential growth
Definition
Each new fission cycle increases the population by a factor of 2
Term
Growth curve
Definition
In laboratory studies, populations typically display a predictable pattern over time
Term
Lag phase
Definition
“flat” period of adjustment, enlargement; little growth
Term
Exponential growth phase
Definition
a period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment
Term
Stationary phase
Definition
rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants
Term
Death phase
Definition
As limiting factors intensify, cells die exponentially
Term
Turbidometry
Definition
method of analyzing population growth; most simple; degree of cloudiness, turbidity, reflects the relative population size
Term
Enumeration of bacteria
Definition
method of analyzing population growth; Viable colony count; Direct cell count – count all cells present; automated or manual
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