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40 Cards in this Set

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  • Back
have optimum growth at ph0-ph6 example:mold and yeasts
have optimum growth at ph8.0-ph14
effect of ph on growth:
extremes in ph denature enzymes and inhibit microbial growth.
have optimum growth at ph6.5-ph7.5
includes most microbial species example: most common
concentration of hydrogen ions (H+). ph scale extends from 0-14
solutions that maintain constant ph.this is included in media to maintain optimum ph for growth.
cardinal tempatures
maximum temp.- highest temperature at which growth occurs
cardinal tempatures.
minimum temp.- lowest temp. at which growth occurs.
cardinal tempatures
optimum temp.- temperature at which best growth occcurs.
have optimum growth at 0C - 20C. these are rare in our area but they are found on ocean floors and polar region.
have optimum growth 25C-40C but growth is best at 30%C. most microbial species including normal flora and pathogenic microbes.
mesophiles that can grow below 20C but optimum growth is above 25C. some spoil food in frig. example: Listeria monocytogenes is pathogenic psychrotroph that causes listeosis and can cause damage to fetus.
grow best at 40C- 100C these have enzymes that are heat stable
grow optimally at 80C-100C found in compost piles, hot springs, and geysers.enzymes used in PCR PROCESS.
obligate Aerobes
require atmospheric level of free O2 (21%) example: Mycobacterium tuberculosis
require less than 21% free O2 for optimal growth
does not use free O2
facultative anaerobe
use free O2 when available but can also grow without it.
aerotolerant anaerobe
never use O2 and are indifferent to it. example: Lactobacillus acidophilus
obligate anaerobes
can not tolerate free O2 and die in its presence lack SOD and catalase needed to break down toxic products when O2 is used cultivating using reducing agents and environments that remove free O2 example: Clostridium tetani
also require 3%-10% CO2 for optimal growth can be cultivated in candle jar example: Nesseria meningitidis
obligate halophile
require 15%-30% salt their location is the dead sea and salt pits.
falcultative halophiles
grow in isotonic environment and in 2%-10% salt example: Staphylococcus
number of bacteria per ml of culture.
explain ehat happens in each of the following stages
FIRST: (lag stage)
cells adjust to enviroment and prepare to divide no binary fission
SECOND: (logarithmic phase)
bacteria divide at constant maximum rate.
THIRD: (generation time)
interval for doubling number maintained for genetic engineering
FORTH: (stationary phase)
growth rate equals death rate number in population constant(1010/ml)
FiFTH: decline (death phase) phase
bacteria die at accelerated rate death due to depletion of nutrients and build up of wastes to toxic level.
direct methods
cell counts
indirect methods
colony counts or effects produced as numbers vary
increase in cloudiness indicates increased titer spectrophotometer measures absorbtion of light and turbidity of cultures
serial dilution
an example of sample or culture
active sites
areas where substate(s) attach these are present on all enzymes
lock-and-key mechanism
fit between enzyme and substrate
allosteric sites
areas where molecules other than substrates attach usually inhibit and called allosteric inhibitors
simple enzyme
proteins with catalytic activity
complex enzyme
inactive protein plus cofactor