Ch. 18 -- Evaluation of Media Flashcards
Carbon
all bacteria require ________ to build organic molecules
Autotroph
“self-feed” – an organism that utilizes inorganic carbon (CO2) as their source of carbon – ex: Cyanobacteria
Heterotrophic
organisms cannot synthesize organic molecules from CO2 – preformed organic molecules in their environment as carbon sources
Fastidious
requires a variety of growth factors and nutrients from the environment and will not grow well if factors are not present
Media
something on which we grow bacteria – classified either as complex (undefined) or chemical defined
Complex Medium
uses preparations of extracts from other organisms – the exact amount of each content is unknown
Chemically Defined Medium
contains pure organic or inorganic compounds added in finite amounts – the exact compostion is known
Enriched Medium
media to which specific nutrients are added to support the growth of fastidious organisms – like blood agar
Blood agar
enriched medium, contains blood which provides nutrients such as iron and protein for fastidious organisms
Chocolate agar
heated blood agar
EMB agar
growth on this medium tells us the bacteria is gram negative
Spectrophotometer
an instrument used to determine bacterial cell numbers – measures cell density or turbidity – the machine direct light through a sample, which either scatters, absorbed and passes through – the more cells, the less light passes through
Absorbance
is a measurement of the amount of light absorbed or dispersed by the specimen – directly proportional to cell number, more cells, more absorbance
Transmittance
measure of how much light passes through the sample, more light, less cells, inversely proportional to cell numbers
