Final answer:
The hydroxyl group is found at the 3' end of a DNA strand, while the phosphate group is found at the 5' end.
Step-by-step explanation:
The chemical group found at the 3' end of a DNA strand is the hydroxyl group. This hydroxyl group is connected to the 3' carbon of the sugar molecule in the DNA nucleotide. On the other hand, the chemical group found at the 5' end of a DNA strand is the phosphate group. This phosphate group is connected to the 5' carbon of the sugar molecule in the DNA nucleotide.