gel electrophoresis- lqc 2b Flashcards
what is gel electrophoresis used for?
the separation of differently sized dna fragments
label this
role of agarose gel in gel electrophoresis
Provides a matrix to enable the separation of the different sized DNA fragments. Small fragments are able to move more easily through.
role of wells in gel electrophoresis
DNA is put in these so that when potential difference is applied the DNA will move through the gel.
role of dna loading dye in gel electrophoresis
Helps DNA sink to the bottom of the gel well and not diffuse out of the well into the buffer. Allows progress of electrophoresis to be seen.
role of TAE buffer in gel electrophoresis
Maintains a constant pH to prevent denaturation of DNA. Helps keep the gel cool when the electric current is applied. Helps the conduction of the electric current.
role of anode and cathode in gel electrophoresis
Allows a potential difference to be created across the gel so that DNA fragments move through the gel
role of dna ladder in gel electrophoresis
This is a sample of DNA fragments of known length i.e. 500 base pairs. Helps determine the size of the DNA fragments in the actual sample.
describe how and why dna moves through the gel
A potential difference is created across the gel between the two electrodes. The cathode (- ve, black) is at the end where the gel wells are located and the anode (+ ve, red) is at the other end. DNA fragments move through the gel based on their charge and separate based on their size. DNA is negatively charged so moves towards the positive anode. Smaller fragments can move more easily through the gel matrix and so move faster and further through the gel. The gel retards the larger fragments so they stay closer to the cathode.
