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35 Cards in this Set

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Name the physical control methods with heat
direct flame, hot-air oven, boiling water, autoclave, pasteurization, and High temperature-short time (flash pasteurization)
what what physical control method removes microorganisms larger than the pore size of the filter? and what is the size needed to remove virus's?
filtration, typical pore size is .2-.45 um, .1 um required to remove viruses
How does UV light work?
Adjacent pyrimidines link together forming dimmers, often used to control microbes in air, favorite method for sterilization of large surface areas
Differeniate between thermal death time and thermal death point
thermal death time-time necessary to kill a microorganism at a given temperature, thermal death point-lowest temperature required to kill a liquid culture of a certain species in 10' at pH 7.00
Differentiate between ionizing radiation and ultraviolet radiation and their effects on microbial cells
Ultraviolet Light (none ionizing irradiation)
a. adjacent pyrimidines link together forming dimmers
Ionizing radiation: use cobalt 60 cause damage by forming free radicals which attack DNA
What organism is the "world's toughest" bacterium?
Deinococcus radiodurans
What two bacterial species are contained on a test strip in order to test if sterilization has been sucessful?
Bacillus stearothermophilis and Bacillus subtilis
Are gram + or gram - bacteria more sensitive to radiation?
Gram positive
What effect of moist heat on microorganisms is destrcution of proteins by the process of?
oxidizes proteins and dehydrates cells
Pasteurization, known as "low temperature, long time" is done how?
62.9C for 30'
Flash pasteurization, HTST done how?
140C for 3s
Describe the autoclaves operating conditions
15 psi, 121.5C, 15'
HEPA filters remove how many particles?
99%
Describe the methods availible for long-term storage of bacterial cultures
Deep freezing-40% glycerol used, stored in -70C
Lyophilization-stored -70C and water removed through use of vacuum
What are the 3 categories of hemolytic activity observed by bacteria on blood agar plates? Differeniate.
Beta-bacteria completely lyse RBSs, results in clearing of colony
Alpha-incomplete hemolysis causes geening area around colony
Gama-absence of hemolysis
What are the 3 genera of bacteria collectivelly called rhizobia?
Rhizobium, Bradyrhizobium, Azorhizobium
What is ment by the Rhizosphere effect?
bacteria chemotically attracted to roots due to secreation of flavoniod compounds
How are cyanobacteria important to the agriculture of asia?
Anabaena azollaw important to rice farming
Why are lichens considered biosensors?
sensitive to air quality
How do symbiotic plant-microbe relationships of Azosprillium differ from those of Frankia and the rhizobia?
Azospirollium lives between root cells (intercellular) and dont induce root nodules
What is the different between defined media and complex media?
Complex-cannot be sure of components or quanity
Defined-ingrediants and amounts known
Describe the symbiotic relaitonship of mycorrhiza
Fungi and roots of vascular plant
Describe the symbiotic relationship that forms lichens
fungi and algae or cyanobacteria
Differentiate between the following:mutualism, commensalism and parasitism
mutualism-positive for both
commensalism-one organism benefits doesnt help/harm other
parasite-one organism benefits at expense of host
How does the relationship between the giant amoeba Pelomyxa palustris and one of the bacterial endosymbionts provide evidence for the endosymbiotic theory of cellular evolution?
internal structures resemble cristea of mitochondria
Describe essential symbiotic relationship between ruminants and microorganisms
microorganisms help to digest materials and microbes get food
mechanism for henol/phenolic compounds
denatures proteins, especially in cell wall
Cresols (mentholated phenol)
denatures proteins, it has the ability to reduce surface tension by loosening bacteria from tissue allowing greater penetration of antiseptic
Alcohols
denatures proteins and dissolves lipids, cell membrane disintegration, strong dehydration agents
Soaps
emulsify oily layer of the skin along with mucrobes is broken up and vanishes down with water being rinsed
Cationic detergents
derivatives ammonium chloride containing four organic groups in place of the four hydrogens at leadt one group long alkyl group
Negatively charged lipid membrane of bacterial cell attracts positively charged bacterial components of cationic detergent molecule
Chlorine
free chlorine added directly to water a reaction occurs form hypocholorous acid
Alkylating agents
attach methyl or ethyl group to proteins and DNA, rendering molecules nonfunctional and causing death of microorganisms
Reacts with amino and hydroxyl groups of nucleic acids and proteins and carboxyl and stulfhydryl groups in proteins inserting an alkyl between them
Heavy metals
Brings to sufhydryl groups of proteins and denature them
Acids
mechanism of action and damage microbial membranes and interfere with the uptake of certain essential organic substances like amino acids