The DNA segment

To create a DNA probe labeled with 32-$$\mathrm{P}$$at the 5′ ends, The DNA segment is dephosphorylated using alkaline phosphatase followed by the addition of 32P from gamma-labeled ATP using polynucleotide kinase

The DNA segment is dephosphorylated using alkaline phosphatase followed by the addition of 32P from alfa-labeled ATP using polynucleotide kinase The DNA segment is dephosphorylated using Klenow polymerase, followed by the addition of 32P from beta-labeled ATP using the polynucleotide kinase