Midterm 2 Group 2 Microbiology

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essential nutrient

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any substances that must be provided to an organism

consist of macronutrients (required in large quantitites, play principal roles in cell structure and metabolism, C, H, O) and micronutrients (trace elements, involved in enzyme function and maintenance of protein structure, Mn, Zn, Ni)

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sources of nutrients (six main ones)

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carbon, nitrogen, oxygen, hydrogen, phosphorus, sulfur

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Carbon Nutrient Sources

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majority are organic

heterotroph: must obtain C in organic form (nutritionally dependent on other things)

Autotroph: Uses inorganic CO2 as its carbon source (not nutritionally dependent on other living things)

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Nitrogen Sources

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mainly from N2

heterotrophs get it from proteins, DNA, RNA

bacteria and algae use inorganic nitrogenous nutrients

some can transform N2 into usable compounds by nitrogen fixation

must be converted to NH3 because it is the only form that can combined with C directly to make amino acids and other compounds

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Oxygen Sources

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O is a major organic compound component

in inorganic salts

O2 is 20% of atmosphere

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Hydrogen Sources

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H is a major component of all organic and several inorganic compounds

maintain pH, forms hydrogen bonds, source of free energy in oxidation-reduction reactions of respiration

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Phosphorus (Phosphate) Sources

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main inroganic source of phosphorus is phosphate (PO4 -3)
-comes fro phosphoric acid
-found in rocks and oceanic mineral deposits

key component of nucleic acids

found in ATP

phospholipids in cell membranes and coenzymes

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Sulfur Sources

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in environment in mineral form

essential part of some vitamins

amino acids- methionine and cysteine

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Other Sources

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potassium- protein synthesis, membrane function
sodium- cell transport
calicum- cell wall stabilizer, endospores
magnesium- cholorphyll and stabalizes membranes and ribosomes
iron- cytochrome proteins
zinc- regulatory element for euk. genetics, binding factors for enzymes
copper, cobalt, nickel, molybdenum, manganese, silicon, iodine, boron- needed in small amounts by some microbes

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What are growth factors?

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essential organic nutrients

def: an organic compound such as an amino acid, nitrogenous base, or vitamin that cannot be synthesized by an organism and must be proved as a nutrient

ex. must get some amino acids from food (essential amino acids)

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How do microbes feed?

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Phototrophs-
microbes that photsynthesize

Chemotrophs-
microbes that gain energy from chemical compounds

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Photoautotrophs

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photosynthetic

from the basis for most food webs

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Chemoautotrophs

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use organic compounds for energy and inorganic compounds as a carbon source

LITHOAUTOTROPHS: rely totally on inorganic minerals

METHANOGENS: produced methane from hydrogen gas and carbon dioxide
-ex. archae
-some live in extreme enviroments

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Chemoheterotrophs

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majority of hetertrophs are chemoherterotrophs.

derive both carbon and energy from organic compounds

SAPROBES: free living microorgranisms, feed on organic detritus from dead organisms, decompose plant litter, animal matter, dead microbes, rigid cell wall (release enzymes to the extracellular enviroment and digest food particles to smaller)

obligate saprobes- exists only on dead organic matter in soil and water

faculative parasite- when a saprobe infects a host, usually when the host is compromised (like an opportunistic pathogen)

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Parasites

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type of chemoherterotroph

get nutrients from cells/tissues of a host

also called pathogens (cause damanage to tissues or death)

ectoparasites- live on the body
endoparasites- live in organs and tissues
intracellular parasites- live within cells
obligate parasites- unable to grow outside of a living host

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Osmosis

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diffusion of water through a selectively permeable membrane

selectively permeable- having passageways that allow free diffusion of water but can block other things

water diffuses from lower concentration to higher (goes to side with less water)

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Hypotonic examples

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bateria cell wall protect them from bursting

ameoba has a water vacuole that moves excess water out of the cell

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Hypertonic examples

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halobacteria living in the great salt lake absorb salt to make thier cells isotonic with the environment (isotonic=same)

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Diffusion

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when atoms or molecules move in a gradient from an area of higher concentration to an area of lower

random thermal movement

determined by permeability and concentration gradient

simple or passive diffusion-limited to small nonpolar molecules or lipid soluble molecules

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Facilitated Diffusion

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carrier protein, binds to a specific substance, changes conformation of carrier, substance moved across membrane

carries exhibit specificity

SATURATION: the rate of a substance is limited by the number of binding sites on the transport proteins

COMPETITION: when two molecules of similar shape can bind to the same binding site on the carrier protein

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Active Transport

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against the diffusion gradient, or in the same direction as diffusion gradient but at a faster rate than simple diffusion

need specific membrane proteins or pumps

needs energy

monosaccharides, amino acids, organic acids, phosphates, metal ions all need it

GROUP TRANSLOCATION: couples the transport of a nutrient with its conversion to a substance that is immediately useful inside the cell

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Endocytosis

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active transport form

cell encloses the substance in its cell membrane simultaneously forming a vacuole and engulfing it

phagocytosis

pinocyctosis

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environmental factors that influence microbes

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temp- they take the temp of their surroundings

they have a min, max, and optimum (cardinal) temp that they can grow and metabolize at

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Psychopile

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microorganism that has an optimum temp below 15 C and is capable of growth at 0 C.

obligate to cold, can't grow over 20 C.

Psychrotrophs or faculative psychorophiles grow slowly in cold but have an optimum temp above 20 C

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Mesophile

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grows at intermediate temps

20 C to 40 C

temperate, subtropical, tropical regions

most human pathogens have optima between 30 C and 40 C

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Thermophile

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grows optimally at greater than 45 C.

rnage is 45 C to 80 C.

hyperthermophiles- grow between 80 C and 120 C.

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Gas for microbes

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most important is O2, also CO2

when oxygen enters cellular reactions, it transformed to toxic products

-cells developed enzymes that go about scavenging and neutralizing
-ex. superoxide dismutase, catalase
-essential for aerobic organisms

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Aerobe

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can use gaseous oxygen in its metabolism and possesses the enzymes needed to process toxic oxygen products

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obligate aerobe

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cannot grow without oxygen

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facultative anaerobe

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an aerobe that does not require oxygen for its met. an dis capable of growth in the absence of it

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microaerophile

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does not grow at normal atmospheric concentrations of oxygen but requires a small amount of it in met.

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anaerobe

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lack the met. enzyme systems for using oxygen in respiration

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strict, obigate anaerobes

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also lack enzymes for processing toxic oxygen and cannot tolerate any free oxygen in the immediate environment and will die if exposed to it

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Aerotolerant anaerobes

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do not utilize oxygen but can survive and grow to a limited extent in its presence.

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_____ grow best at higher Co2 tension than is normally present in the atmosphere

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capnophiles

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Obligate acidophiles

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usually organisms grow in pH 6 to 8

Euglena mutabilis- alga that grows between 0 and 1 pH.

Thermoplasma- archae that lives in hot coal piles of a pH to 1 to 2, would lyse if exposed to pH 7

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Osmophiles

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live in habitats with a high solute concentration

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Halophiles

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prefer high concentrations of salt

obligate halophiles- grow optimally in solution of 25% NaCl but require at least 9% for growth

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Barophiles

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deep-sea microbes that exits under hydrostatic pressures ranging from a few times to over 1,000 times the pressure of the atmosphere

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Symbiosis

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situation where two organisms live together in a close relationship

mutualism
commesalism
satellitism
parastism

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Mutualism

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when organisms live in an obligatory but mutually beneficial relationship

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Commensalism

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the member called the commensal receives the benefits, while its coinhabitant is neither harmed nor helped

satellitism: when one member proves nutritional or protective factors needed by the other

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Parasitism

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a relationship in which the host organism proves the parasitic microbe with nutrients and a habitat

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Nonsymbiotic Relationships

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free living organisms, and the relationships are not required for survival

synergism

antagonism

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Synergism

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an interrelationship b/w two or more free living organisms that benefits them but is not necessarily for their survival

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Antagonism

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an association b/w free living species that arises when member of a community compete
-one secretes chemical that kills others

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Normal Microbiotia

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microbes that normally live on the skin, in the alimentary tract, and in other sites in humans

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What two level does microbial growth take place?

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cell synthesizes new cell components and increases in size

number of cells in the population increases

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What is the basis for population growth?

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Binary Fission

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Generation (Doubling) Time

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the time required for a complete fission cycle

each cycle increases the population by a factor of 2

average generation time 30 to 60 minutes

pattern is exponential

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Graphing Bacterial Growth

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logarithmically- straight line
arithmetically- constantly curved slope

size of population over time:

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Graphing Bacterial Growth

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logarithmically- straight line
arithmetically- constantly curved slope

calculate the size of population over time:
N (sub f) = ( N (sub i)) 2 (to the N)

N f is the total number of cells in the population at some point in the growth phase

N i is the starting number

N denotes the generation number

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Stages in a normal growth curve

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lag phase

exponential growth phase

stationary growth phase

death phase

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Lag Phase

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"flat" period

happens while newly inoculated cells adjust, enlarge, sythesize

not yet multiplying at max rate

population so sparse, sampling is missing them

length of period varies

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Exponential Growth (Logarithmic or log) Phase

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growth curve increases geometrically

cells reach max rate of cell %

continues as long as cells have adequate nutrition and favorable environment

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Stationary Growth Phase

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pop enters a survival mode, cells stop growing or grow slowly

rate of cell inhibition or death balances out rate of multiplication

depleted nutrients and oxygen

excretion of organic acids and other biochemical pollutants into the growth medium

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Death Phase

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curve dips down

cells begin to die at exponential rate

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What is a chemostat?

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continuous culture system

used to see stages of infection, culture techonology ect.