Chromosome damage

Somebody tells you that a single ultraviolet photon carries an energy equivalent of about 10
electron volts (eV, see Appendix B). You propose a damage mechanism: 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?

(Heat produced) = (mechanical energy input) * (0.24 cal/J)

so that

Heat produced = 3.84E-19 cal

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Ygggdrasil
Gold Member
2019 Award
That's a good first step. Now you need to convert that energy into a change in temperature. To do this, you need to find the mass of a typical cell nucleus by finding the volume and assuming it has the same density as water (typically a good assumption when working with cells).

Assuming a cell nucleus diameter of ca 2 micrometers and mass density equal to that of water, the mass of the nucleus is 4E-15 kg.

I'm not sure how to calculate the temperature rise. Can I simply use

$$\Delta E_k = \frac{3}{2} k_B \Delta T$$

as for gases?

Last edited:
Ygggdrasil
Gold Member
2019 Award
You'd have to use the more general formula

q = mcΔT

Where q is the amount of heat transfered, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

Should I assume the same specific heat capacity as water too?

Ygggdrasil