DNA molecules are typically folded tightly. Stretching a strand of DNA means straightening it, and the molecules resist this straightening. Investigators can attach beads to the ends of a strand of DNA and, using “optical tweezers,” measure the force required to produce a certain extension. Data for the stretch of a 3500 base pair strand of DNA approximately follow the line in the graph in Figure P8.58. What is the spring constant for this strand of DNA?

Transcribed Image Text:

FIGURE P8.58 Restoring force (pN) 0.06 0.04 0.02- 0 0 50 100 150 200 Extension (nm)