Lab 12b Agarose gel electrophoresis

How are DNA fragments separated & visualized?

  • a sample loading buffer containing two blue dyes is added to the DNA solution

What is loading dye used for?

  • makes it easier to load the gels and monitor the progress of the DNA electrophoresis

Which moves faster and farther, short or long DNA fragments?

  • the faster dye comigrates with DNA fragments of approximately 500 bp

  • the slower dye comigrates with DNA fragments of approximately 5kb or 5,000 bp in size

What is the marker or ladder for?

  • to estimate the size of the DNA bands in their experimental samples by comparing them to the closest fragment in the ladder

How would you use the migration pattern of a marker or ladder to determine the size of a fragment of unknown size?

  • graphing size of unknown fragments from DNA standards against the distance each DNA band moves through the gel, generating standard curve

  • number of base pairs