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process bywhich chemical substances (nutrients) are acquired from the environment and used in cellular activities


must be provided to an organism

essential nutrients

requited in large quantities, play principla roles in cell structure and metabolism


reuired in small amounts, involved in enzyme function and maintenance of protein structure

micronutrients or trace elements

contain carbon and hydrogen atoms and are usually the products of living things. ex, methane(CH4), carbs, lipids, proteins and nucleic acids

organic nutrients

atom or molecule that contains a combination of atoms other than carbons or hydrogen. ex.-metals and their salts, Magnesium sulfate, ferric nitrate, sodium phosphate, geses-O2 and H20

inorganic nutrients

chemical analysis of microbial cytoplasm

70% water, 96% of cells composed of carbon,hydrogen,oxygen,phospohorous,sulfur and nitrogen

must obtain carbon in an organic form made by other living organisms such as proteins, carbs, lipids and nucleic acids.


an organism that uses CO2 , an inorganic gas as it carbon source. Not nutrionally dependent on other living things


main reservoir of essential nutrients

nitrogen gas, 79% of earth's atmosphere

makes up 20% of earth's atmosphere


major element in all organic compunds and several inorganic

water, salts and gases

roles of H2

maintaining pH, acceptor of O2 during cell respiration,

the main inorgainc compund

phosphate, found in rocks and oceanic materail

key component of nucleic acids and essential to genetics


essential to protein synthesis and membrane formation


important to some types of cell transport


cell wall and endospore stabilizer


component of chlorophyll, a membrane and ribosome stabilizer


component of proteins of cell respiration


organic counds that can't be synthesized by an organism because they lack the genetic and metabolic mechanisms to synthesize them

essential organic nutrients

must be provided as a nutrient

growth facors

gain energy from chemical compounds


gain energy through photosynthesis


two categories if areobic respiration

saprobes-free-living organisms that feed on organic detrius from dead organisms
Parasites-derive nutrients from host

bacteria that exust as normal flora but can cause disease

opportunistic pathogen

can live off host or derive their own nutrients

facultative parasite

doesn't require energy, exist in a gradient and move from higher to lower concentration

passive transport

requires a carrier for diffusion

facilitated diffusion

requires energy and carrier proteins, gradient independent

active transport

net movemnet of molecules down their concentration gradient


totality of organisms to make their own habitat


3 cardinal temeratures

minimum-lowest permitting micribial growth
maximum-highest permitting microbial growth
optimun-promotes fastest rate of growth and metabolism=37 deg C or 98.6 F

3 temperature adaptation groups

psychrophile-optimum temperature below 15 deg C can grow at 0 Deg C
Mesophiles-optimum temp 20-40 deg C
Thermophiles-optimum temp greater than 45 deg C

cells that have developed ezymers to neutralize toxic products(oxidative processes)

superoxide dismutase, catalase

microbes that must live in an oxygen free environment


microbes that utilize oxygen and can detoxify it


can't grow without oxygen

obligate aerobe

ultilizes oxygen but can also grow without it

facultative anerobe


requires only a small amount of oxygen

lacks the enzyme to detoxify oxygen and can't survive in an oxygen environment

obligate anerobe

don't utilize oxygen but can survive and grow in its presence

aerotolerant anerobes

all microbes require this compound in their metabolism


grows best at higher CO2 tensions than normally present in atmosphere


majority of organisms grow at a pH of

between 6 and 8

grow at extreme acid pH

obligate acidophiles

grow at extreme alkaline pH

extreme alkalinophiles

require a high concentration if salt


don't require high concentration of solute but can tolerate it when it occurs


can survide under extreme pressure and will rupture if exposed to normal atmospheric presure


obligatory, dependent, both members benefit


commensal members benefit, other member neither harmed nor benefited


parasite is dependent and benefits,host is harmed


members cooperate to produce a result none could do alone


actions of one organism affect the success or survival of others in the same community(competition)


nonpathogenic residential flora in the human body such as symbiotic bacteria, fungi and a few protozoa

normal microbial flora

result when organisms attatch to a substrate by some form of extracellular matrix that binds them together in complex organized layers. They dominate the structures of most natural enviroments on earth.


communicate and cooperate in the formation and function of biofilsm

quorum sensing

the two levels of microbial growth

increase in size and increase in population

divion of bacterial cells occurs mainly through. the process involves a parent cell that inlarges, duplicates its chromosome and forms a central transverse septum diving the cell into 2 daughter cells

binary fission

time required for a complete fission cycle of bacteria(doubling time)


when each fission cycle increases the population by a factor of 2

exponential growth

equation for calculating population size over time


when populations typically display a predictable pattern over time in laboratory studies

growth curve

lag phase-flat period of adjustment, exponential growth phase-period of maximum growth, stationary phase-rate of cell growth equals rate of cell death by depletion of nutrients and 02, death phase-limiting factors intensify,cells die exponentially

stages of normal growth curve

measures cloudiness, turbidity, reflects the relative population size. the opaqueness of liquid. simplest way to count bacteria


counts all cells present, automated or manual

direct cell count

The complete conversion of superoxide(O2-) ion into harmless oxygen requires a two-step process using these two enzymes(test question)

superoxide dismutase and catalase

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