Question

Consider the polytene chromosomes of the salivary glands of Drosophila virilis. If the glands are stained with aceto-orcein, and then one salivary gland is incubated (heat shocked) at 37 deg C, and the other is left at 25 deg C...

a) Should there be any [observable] differences between the two temperature treatments? If yes, what are they?
b) Should there be more DNA puffs in the treatment at 37 deg C or in the treatment at 25 deg C? Why?

Answer 1

The first part I will explain it with a drawing:

For the part B, yes it should because the heat treatment can denature the proteins (Histones) that keep the chromosomes packed