a. Somebody tells you that a single ultraviolet photon carries an energy equivalent of ten electronvolts (eV, see Appendix B). You suspect that the damage mechanism is that a photon delivers that energy into a volume the size of the cell nucleus and heats it up; then the increased thermal motion knocks the chromosomes apart in some way. Is this a reasonable proposal? Why or why not? [Hint: Use Equation 1.2, and the definition of calorie found just below it, to calculate the temperature change.]
Equation: (heat produced) = (mechanical energy input) × (0.24 cal/J).
b. Turning the result around, suppose that that photon's energy is delivered to a small volume L3 and heats it up. We might suspect that if it heats up the region to boiling, that would disrupt any message contained in that volume. How small must L be in order for this amount of energy to heat that volume up to boiling (from 30?C to 100?C)? What could we conclude about the size of a gene if this proposal were correct