Chapter 6 Flashcards
Nutrition and Growth
Microbial growth is what
high population of microbes due to reproduction
Results of microbial growth
Colony and Biofilm
Colony def
an aggregation of cells arising from single parent cell
biofilm def
microbes adhering to a surface in a complex community. ex. dental plaque
biofilms do what
adherent community of microbes
extracellular matrix (protection)
what are the steps of biofilm
protein absorption, bacterial adsorption, bacterial attachment, bacterial growth, biofilm formation, biofilm detachment
benefit of biofilms
increased drug tolerance, immune evasion
organisms use a variety of ____ for their energy needs
nutrients
Nutrient —-> what
catabolism —–> anabolism
what are 3 common nutrients
Oxygen, Carbon, Nitrogen
oxygen is essential for what
obligate aerobes
oxygen is deadly for what
obligate anaerobes
how can oxygen be deadly
it can take on toxic forms that are highly reactive and excellent oxidizing agents
how do aerobes counteract the oxygen radicals
by producing enzymes
Obligate Aerobes and oxygen
they require O2
Obligate anaerobes and oxygen
they are killed by O2
faculative anaerobes and oxygen
they like O2, but dont need it
aerotolerant anaerobes and oxygen
they are unaffected by O2
what are ecoli (o2 related)
faculative anaerobes
pure culture def
a population of microbes where all are descendants of the same organism
medium def
anything in or on which we grow a microbe
it contains nutrients for the microbes
solid medium name
agar
liquid medium name
broth
inoculum def
microbes which are added into media
where can we obtain microbes
environmental, clinical, stored
obtaining pure cultures ex
example is aseptic technique
progenitor is termed what
a colony forming unit
Aseptic technique prevents what
the combination of sterical substances, microbial cultures, or objects
why is contamination bad?
removes the validity of experimental results
what are some potential sources of contamination?
tools, equipment, eht environment, the scientists
what does insufficient nitrogen lead to
no anabolism
anabolism def
Anabolism is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units
what is nitrogen fixation essential to
to life on earth
what does nitrogen fixation convert nitrogen gas into
into usable nitrogen
what can nitrogen fixation be applied to
agricultual applications
what are the different sources of carbon called
autotrophs and heterotrophs
energy sources
light and chemical compounds
carbon sources
co2 and organic compounds
CO2 and light leads to what
photoautotrophs
CO2 and chemical compounds leads to what
chemoautotrophs
Organic compounds and light leads to what
photoheterotrophs
organic compounds and chemical compounds leads to what
chemoheterotrophs
what does temperature affect
affects 3d structure and function of proteins
are membranes sensitive to temperature
yes
if temp is too low, what happens to the membranes
they become rigid and fragile
if temp is too high, what happens to the membranes
they become too fluid
how can pH affect things
organisms are sensitive to changes in acididy
neutrophiles are
near neutral pH
acidophiles are what
near acidic habitats
alkalinophiles are what
near alkaline soils and water
halophiles are what
live in salty environments
what do hydrogen ions interfere with
H bonding
what pH best grows bacteria
neutral like 7.3
what pH best grows fungi
lower pH like 5.6
Selective media does what
has a substance that either favors or inhibits growth of a particular micro organism
differential media does what
helps to distinguish differences by presenting a color change to the colony of interest, even though everything grows
Whats special about MacConkey Agar
it is selective and differential at the same time.
describe the bacteria growth curve over time
lag phase, log phase, stationary phase, death phase
where does the microbial growth curve occur
in liquid broth culture
lag phase info
cells spend time adapting to their new environment, they synthesize new components for growth (anabolism)
log phase info
maximum growth, high uniformity, rate of division is constant
stationary phase infor
of viable cells remains constant because the reproductive rate is balanced by death rate. metabolically active.
why do cells enter a stationary phase ?
possible limited nutrients and oxygne, or theres a toxic waste accumilation
death phase info
number of viable cells declines, cells die at a constant rate, no nutrients and a lot of waste
what if theres a long term stationary phase ?
microbial population continually evolves and the number of cells is relatively constatn with small fluctuations. natural selection occurs
in the growth curve, where is natural selection occuring
in long term stationary phases
