The Kb DNA Ladder contains fragments from 1 kb to 10 kb at 1-kb increments, as well as bands at 250 bp, 500 bp, 750 bp, 1500 bp and 12 kb. The band at the ladder's upper end are brighter than those at the lower end, with the transition to higher intensity at the 2-kb band serving as a useful reference point.
Each fragment contains a 5-inch overhang that can be radiolabeled. DNA fragments can also be detected via nonradioactive Southern blot analysis by incorporating fluoresceinated nucleotides into the DNA prior to electrophoresis.
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