Lecture 4 Flashcards
Agarose
most commonly used for DNA
Gel material is non-toxic but most common DNA staining agent ethidium bromide is a carcinogen
Polyacrylamide
polymer material that achieves best separation for protein electrophoresis
The monomer acrylamide is known to be carcinogenic
Caution with exposure when casting the gel
Cellulose acetate
non-toxic, durable material after dried
used in clinical applications for proteins because it is non-toxic
a glucose polymer made into an ester of acetic acid
Native Electrophoresis
Charged particles will move towards oppositely charged plates
Used to separate and identify DNA and proteins
Separation based on charge to mass ratio
PANIC
Positive is Anode
Negative Is Cathode
SDS-PAGE
proteins are denatured by exposure to SDS which is a powerful detergent
DNA Electrophoresis
DNA is negative and the amount of negative charge is proportional to the size of the piece of DNA
Electrophoresis of small DNA fragments separates them by
size because the charge to mass ratio is the same
Smaller fragments tangle less and move through the matrix more quickly
Problem of separating long DNA fragments
the molecules untangle and stretch out like trains
Pulsed Field Electrophoresis (PFGE)
instead of simply applying + and - charges at opposite ends the field, it is pulsed on and off in a leftright direction
has been the accepted standard for characterizing the DNA of pathogens
Reptation
strands to twist and turn and get tangled
The longer the strand, the more tangling, the slower it moves up the gel
Staining/Destaining
Proteins and DNA must be visualized with stains
After electrophoresis performed, the gel with bands is exposed to stain that sticks to protein or DNA more than the gel
Proteins often stained with ?
coomassie blue, Then destained with 5% acetic acid
DNA stained with?
ethidium bromide is visualized under a UV light
Voltages in electrophoresis are?
100’s volts
