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Micro 205- LECTURE GCU
Terms in this set (65)
What breaks down cellulose?
What breaks down lipids?
*lipids--> fats and fatty acids by beta oxidation and then into the TCA cycle
The different nutrient medias
complex media: contain a variety of ingredients, often a digest of proteins
chemically defined media: composed of exact amounts of pure chemicals
What is the purpose of agar?
used to solidify the medium, not destroyed by high temperatures and can be sterilized, liquifies above 95 degrees celcius, solidifies below 45 celcius
The growth curve
the growth of a microbial cell follows a distinct five stage pattern
microbial cells introduced into sterile medium, cells maturing but NOT dividing, increase in size and metabolic rate
**number of cells do not increase
**begin synthesizing enzymes required for growth-metabolically active cells
cells divide at constant rate, generation time can be measured
the bacteria are rapidly increasing in number
*most sensitive to antibiotics
nutrient levels too low to sustain growth
**total numbers remain constant
**some die, others grow and become more resistant to harmful conditions
cells die at a constant rate
exponential, but much slower than cell growth
**total number of viable cells declines
Prolonged Decline phase
some fraction may survive, some adapt to tolerate worsened conditions
What is a pure culture?
all the bacterial cells that result from the replication of a single original bacterial organism, one single species
**Robert Koch contributed most to the techniques developed to obtain a pure culture
What is a biofilm?
an polysaccharide-encased community that most, may enhance bioremediation efforts, and protect organisms against harmful chemicals **hard to get rid of, easy to build up and replicate
What is the medical significance of a biofilm?
May enhance bioremediation efforts, protect organisms against harmful chemicals
What are the different groups of bacteria based on temperature preference?
found in artic and antartic regions
important in food spoilage
this is a comfortable region for pathogens to grow, room temperature
common in hot springs
usually members of archaea, found in hydrothermal vents
Selective media def:
useful for isolating and identifying a specific species of bacteria
**inhibit growth of certain species
Differential media def:
contain a substance that causes microbes to change in an identifiable way
Blood agar medium def:
is differential because bacteria that produce a hemolysin (a protein that causes red blood cells to burst) destroy red blood cells in the medium around the bacterial colony, causing a zone of clear-ing called hemolysis
MacConkey agar def:
-selective: allows only gram negative bacteria to grow because MacConkey agar contain bile salts and crystal violet that inhibit
-differential: the incorporation of the carbohydrate lactose, bile salts, and the pH indicator neutral red permits differentiation of bacteria based on their ability to ferment lactose
Why do we add high concentration of salt and sugar to our food?
Dissolved salts and sugars make water unavailable to a cell, therefore killing the microorganism
**if solute concentration is higher outside the cell, water diffuses out (osmosis)
Fastidious bacteria def:
complicated nutritional requirements ???
Simple stain def:
a very simple staining procedure involving only one stain. You may choose from methylene blue, Gram safranin, and Gram crystal violet. Basic stains, such as methylene blue, Gram safranin, or Gram crystal violet are useful for staining most bacteria
Positive stain def:
when the microorganism is stained and the background is not
Negative stain def:
when the microorganism is not stained and the background is
Gram stain def:
a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents. The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet GRAM NEGATIVE RED GRAM POSITIVE IS BLUE
What is the first staining procedure done on someone who got swabbed for strep throat?
the colonies of Streptococcus pyogenes (the cause of strep throat) produce a clear zone of hemolysis called beta
all the chemical reactions in a living cell
**includes both anabolic and catabolic reactions
Anabolic reactions def:
building up large molecules
Catabolic reactions def:
breaking down of large molecules
reactions involving removal of electrons from a substance
involving addition of electrons or hydrogen atoms to a compound is reduction
speed up conversion of substrate into product by LOWERING ACTIVATION ENERGY
*binds to an active sike, ACT AS CATALYST
small non-protein molecules that can be readily separated from an enzyme, responsible for transfer of atoms from one molecule to another
can assist different enzymes
-include magnesium, zinc, copper and other trace elements
splits glucose into two pyruvates
-generates modest ATP, reducing power, precursors
**doesn't need oxygen
**needs two ATP to get started, yields 4 ATP
What is the fate of carbon atoms in pyruvic acid?
They turn to carbon dioxide molecules
What is the purpose of the TCA cycle?
completes oxidation of glucose, last step
Where does the TCA cycle occur?
inside the cytoplasm
What is the TCA cycle?
produces 2 CO2, 2 ATP, 6 NADH, 2 FADH2
Electron transport cycle occurs where?
-The cell membrane of prokaryotes
-The mitochondria of Eukaryotes
What is the function of electron transport?
the final step in the production of ATP, pass electrons and eject protons to power through, oxygen serves as terminal electron acceptor
What is competitive inhibition?
binds to active site of enzyme, chemical structure similar to a substrate, concentration dependent, blocks substrate
What is non competitive inhibition?
-binds to a different site than the active site
What is feedback inhibition?
end-product binds to the allosteric site of 1st enzyme
-as a result, entire pathway is turned off
-a means of regulating the amount of product produced AND often involves the use of allosteric enzymes
-enzyme activity controlled by binding to allosteric site
-distorts enzyme shape, prevents or enhances binding
-regulatory molecule is usually end product
*allows feedback inhibition
What is the significance of the microbial specimen that lives in the rumen of cows?
the bacteria will produce organic molecules as they obtain energy from the cellulose in grass and replicate the cow will then digest the organic molecules in the bacteria produced to obtain its own energy
Why would whey not be a good food source for fish in a pond or tank?
The fish will die as the microorganisms oxidize it for energy, all the oxygen will be taken, the microorganisms would also kill the fish
Microbial growth def:
increase in number of cells, not cell size
cells divide by binary fission, one cell grows in length and replicates its DNA and then splits into two
streak-plate method def:
simplest most commonly used method for isolating bacteria on a medium, spreads out cells so that individual colonies can grow
prokaryotes grown on agar plans or in tubes don't have nutrients removed and the waste is not removed or replenished
Superoxide distmutase def:
almost all organisms growing in the presence of oxygen produce this enzyme
**inactivates superoxide by converting O2 to H2O2
almost all organisms produce this
**converts H2O2 to O2 and H2O
Biosynthetic reactions def:
reactions or building of complex organic molecules from simpler ones
Endergonic reactions def:
use energy ATP to drive reactions
the capacity to do work
Total ATP gain
theoretical maximum: 38 ATP
temporary, can live without oxygen
where an enzyme binds
Proton Motive Force
Form of energy generated as an electron transport chain moves protons across a membrane to create a chemiosmotic gradient.
it moves twice through
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