Bac Phys Exam 2- Bac Growth

most simple way to measure growth

turbidity

useful countable plate has how many colonies

30-300

in turbidity, light scatter is proportional to

mass

what does a spectrophotometer measure

fraction of incident light measured through culture

OD =

Absorbance

Absorbance =

-logT (transmittance)

Transmittance (T) =

I/I o incident light/intensity after passing through material

transmittance and absorbance are ____. if all light passes through, it’s ____ A and ___ T. If all light is absorbed, it’s ___ A and ___ T

inverse. 0, 100%. infinate, 0.

OD is typically the y axis compared to ___ on the x axis

cells/ml

absorbance in terms of a b c

A = absorbance (OD) x b path length x concentration

beer lambert law is used to determine

concentration

beer lambert law shows a _____ relationship between absorbance and concentration. the ______ line can give concentration of unknown culture

linear. regression

units of a b c for beer lambert

coefficient ml/CFU*cm, cm, CFU/ml

CFU/mL equation

number of colonies/ (dilution (10^x)) x (volume plated mL)

A (absorbance) can also mean

OD600

in cell counting, tryphan blue dyes what cells

dead

for electronic cell counting, cells are put through a ____ and electrical conductivity ______. this causes a ____ ___

pore. decrease. voltage pulse

most direct way to measure growth

dry weight and protein

electronic counting finds

cell number and size distribution

flow cytometry finds

cell-associated flourescence

limitation of viable cell counting

there can be clumps and poor plating can lead to underestimation of viability

dry weight/protein finds ___. limitation is

biomass. slower and destructive

CFU/mL on a plate estimates

cells’ ability to form colonies

limitation of CFU/mL counting colonies

some can be clumped together, so it could be an underestimate

what should you blank the spectrometer with

uninoculated medium

when interpreting OD and CFU/mL together, a steady OD does not mean

viability

two A equations

-log10T and abc