elements required in trace amounts (often supplied in water or in media components)
what are the microelements (trace)?
Mn, Zn, Co, Mo, Ni, and Cu
why do organisms need carbon?
-it is the backbone of all organic components present in the cell -source of this often supplies hydrogen, oxygen and electrons
hydrogen and oxygen come from what?
Why are electron important?
play a role in energy production and reduction of CO2 to form organic molecules
what are heterotrophs?
use organic molecules as carbon sources which often also serve as energy source
what are autotrophs?
-use carbon dioxide as their sole or principal carbon source -must obtain energy from other sources
what are phototrophs?
use light as energy source
what are chemotrophs?
obtain energy from oxidation of chemical compounds
what are lithotrophs?
obtain electrons from reduced inorganic substances
what are organotrophs?
obtain electrons from organic compounds
requirements for N, P, and S
-needed for synthesis of important molecules (amino acids, nucleic acids)
what are the sources of nitrogen?
-organic molecules -ammonia -nitrate via assimilatory nitrate reduction -nitrogen gas via nitrogen fixation
what is the source of phosphorus?
inorganic phosphorus usually as inorganic phosphate
what is the source for sulfur?
usually supplied as sulfate via assimilatory sulfate reduction -
what are growth factors?
-organic compounds -essential cell components that the cell cannot synthesize -must be supplied by the environment of cell is to survive and reproduce
what are the classes of growth factors?
-amino acids (needed for protein synthesis) -purines and pyrimidines (needed for nucleic acid synthesis) -vitamins (function as enzyme cofactors)
what are the applications of growth factors?
-use of MOs in bioassays to quantify growth factor -industrial production of growth of factors by MOs
what are the methods of nutrient uptake?
-passive diffusion -facilitated diffusion -active transport -group translocation
what is pasive diffusion?
-molecules moving from a region of higher concentration to an area of lower concentration because of thermal agitation
what molecules move by passive diffusion?
water, oxygen, and carbon dioxide across cell membranes
what is facilitated diffusion?
-NOT energy dependent -direction is from area of high concentration to low concentration but uses carrier molecules the transport -need less of a gradient than passive dif. MORE PROMINENT IN EUKARYOTES THAN IN PROKARYOTES
what molecules are transported by facilitated diffusion?
glycerol, sugars, and amino acids
what is active transport?
-energy dependent -moves molecules AGAINST the gradient -concentrates molecules inside the cell -involves carrier proteins (permeases)
what provides the energy for active transport?
ATP or proton motive force
what effect is seen in facilitated diffusion as well as active transport?
carrier saturation at high solute concentrations (max amount that can be carried at one time therefore causing max rate of transport)
what are ABC transporters?
-ATP binding cassette transporters -seen in bacteria, archaea, and eukaryotes -move molecules across the membrane with aid of ATP hydrolysis
what is group translocation?
-chemically modifies the molecule as it is brought into the cell -energy dependent process
what is the best know group translocation system?
-sugar phophotransferase system (PTS) -transports sugars while phosphorylating them using phopshoenolpyruvate (PEP) as the phosphate donor
-ferric iron is very insoluble so uptake is difficult -microorganisms use siderophores to aid uptake -siderophore complexes with ferric iron -complex is then transported into the cell
how is culture media classified?
-by chemical constituents -physical nature -function
what is defined/synthetic media?
all components and concentrations are known
what is complex media?
contain some ingredients of unknown composition and/or concnetration
what are some common media componets?
PEPTONES: protein hydrosylates prepared by partial digestion of various protein sources EXTRACTS: aqueous extracts, usually of beef or yeast AGAR: sulfated polysaccharide used to solidify liquid media
what is supportive media?
functional media that supports the growth of many microorganisms (tryptic soy agar)
what is enriched media?
functional media that is supplemented by blood or other special nutrients (blood agar)
what is selective media?
-favors the growth of some microorganisms and inhibits the growth of others (Mac Conkey agar which prefers gram -)
what is differential media?
-distinguishes between different groups of microorganisms based on their biological characteristics (ex: blood agar=hemolytic from nonhemolytic/MacConkey=lactose fermenters vs. nonfermenters)
what is a pure culture?
a population of cells that arose from a single cell
what is the pour plate technique?
-sample is diluted several times -diluted samples mixed with liquid agar -mixture of cells and agar are poured into sterile culture dishes
characteristics of colony growth :
-most rapid at the edge of colony (oxygen and nutrients are more available at edge) -slowest at center of colony -in nature, many microorganisms form biofilms on surfaces
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