Gel electrophoresis

Question 1

how does gel electrophoresis separate DNA fragment

Answer 1

1. DNA fragments are loaded into wells of an agarose gel and covered with a buffer solution
2. an electric current is passed through the gel causing negatively charged DNA to move towards the positive electrode at the bottom of the gel
3. DNA fragments then separate according to size as the shorter fragments move faster and travel further through the gel
4. the separated fragments can be viewed directly using UV light or a fluorescent DNA probe to make them visible
5. southern blotting can be then used tp preserve the banding pattern

Question 2

the role of DNA probes

Answer 2

it identifies the target DNA sequence and will bind to it using complimentary base pairing. the DNA probe is tagged with either radioactive phosphorus or a fluorescent marker to make the target fragment visible