Practice question

Random priming generates labeled probes by annealing short random oligonucleotides, usually hexamers, to denatured DNA template to create multiple initiation sites with free 3'-hydroxyl groups. Klenow fragment, the large proteolytic fragment of Escherichia coli DNA polymerase I lacking 5' to 3' exonuclease activity, extends these primers while incorporating labeled deoxynucleotides. Retaining polymerase and 3' to 5' proofreading functions and unable to degrade template, it produces uniformly labeled probes with very high specific activity suitable for Southern blotting, Northern blotting, and colony hybridization.