Week 6 - Electrophoresis Flashcards
(52 cards)
How to identify heavy molecules?
moves slower
How to identify small molecules?
moves more fast and are more charged
Ohm’s law
V/I = R
V=voltage I=current R=resistance
V/I = R
V=voltage I=current R=resistance
What is the medium used in electrophoresis?
agarose, polyacrylamide
What is the capillary used in electrophoresis?
pore size, ionic strength
What determines mobility in electrophorsis?
speed of migration
What happens if we apply constant voltage?
current will eventually increase
because resistance of medium is decreasing
What is agarose gel used for?
DNA
What is polyacrylamide gel used for?
high resolution, proteins and smaller
nucleic acid.
Whats the difference between polyacrylamide and agarose?
smaller pore size of polyacrylamide compared to agarose
- better separation of small molecules
How can capillary achieve high resolution separation?
narrow capillary with buffer
APPLICATIONS OF ELECTROPHORESIS
DNA fingerprinting
DNA sequencing
Protein analysis
Clinical diagnosis – serum proteins, biomarkers
Pharmaceutical development – characterisation of biologics e.g.
antibodies, vaccines
What does higher concentration of agarose mean?
smaller mesh
- more agarose = smaller the sieve
agarose structure
Horizontal
Native structure
What is commonly used at a loading dye in agarose gel?
bromophenol blue, xylene cyano
made also with glycerol
What type of staining is used in agarose gel?
Ethidium bromide, non-toxic fluorescent stains
Ethidium bromide
carcinogenic
What can be determined from agarose gl electrophoresis?
- Size determination
- DNA or RNA extraction
- DNA and RNA
Feature of agarose gel
we can physically cut out band and re-examine
What is a southern blot?
a laboratory technique used to detect specific DNA sequences in a DNA sample
- the samples are chewed up using DNA restriction enzymes normally in intracellular membrane
How to set up a southern blot?
use paper to blot and wick up buffer
start to more liquid/buffer up towards the well so we have gel on top
transfer the membrane on top
put something heavy on it
= we have cellulose membrane with DNA transferred
How do you use a radio cable P32 probe?
incubate membrane with probe
wash off excess
all of prob hydrolyse to particular fragment of DNA that we transferred to membrane
expose to x-ray film
shows restriction image
What does SDS-PAGE involve?
removing tertiary structure
denatured protein (SDS, β mercaptoethanol, boiling)
discontinuous buffer system