Final answer:
The sigmoidal curve in a refractionation of DNA shows the rate of renaturation or hybridization of DNA strands.
Step-by-step explanation:
The sigmoidal curve in a refractionation of DNA shows us the rate of renaturation or hybridization of DNA strands. Refractionation is used to measure how much of the DNA has paired or renatured over time after being separated into single strands. The curve starts off steep, indicating a rapid increase in renaturation at the beginning, and then levels off as the renaturation process slows down.